I have a question

You are correct if the day in question has passed. If the reported speech happened today, then A is correct. If this whole thing happened last week, then D is correct.

In informal American English, the sentence would usually be, "He said he has work tomorrow." A little bit more formal could be, "He says that he will be working tomorrow." but the active tense there is a little uncommon.

"I want to go to the party (tonight) with John, but he said he has to work tomorrow." "I wanted to go to the party (last week) with John, but he said had to work the following day."

Everybody pointing out how they would use a) in informal spoken English is missing the point. This exercise is explicitly meant to learn the formal rules for reported speech, and those are very clear, even if most people don’t follow them in everyday conversation. According to those rules, the tense of the reported speech has to follow that of the main clause, so d) is correct in all cases. Before people crucify me as a prescriptivist: I am not saying at all that this is how everybody should talk. I am just saying that in the context of this exercise, the only clearly (and always) correct answer is d).

I’m a native English speaker and I have no clue what is even happening here. lol

I'm a 52 year old native English speaker. I'm a lawyer. I have another advanced degree. I have no idea why d is correct and a is not.

These tests that one can “watch”, at least based on this example, and the crap that people post constantly in this sub: don’t watch them! Don’t take them! They were clearly not made by native speakers. Usually ALL the answers are wrong in different ways. This is SO painful.

D is the only correct answer. (Even if native speakers might say otherwise, according to the formal grammar rules of reported speech, only D can be correct.) Let’s see why all the others are wrong. A would be correct if the speech verb were in the present tense: “He *says* he has to work tomorrow.” B would be correct if the speech verb were in the past tense, and if we were sure we were reporting it on the same day (we’re not sure): “He *said* he had to work tomorrow.” C’s speech verb is in a present tense, so again the reported verb should also be in a present tense: “He is saying he has to work tomorrow.” D fulfills all of our requirements. It works regardless of which day we are reporting the speech. The speech verb is in the past and accordingly the reported verb has also been made past tense: “He *said* he *had* to work the following day.”

D will always be correct. A would be okay in spoken, casual English if you are reporting on the same day, but should really say, “He said he had to work tomorrow.”

Those don’t mean the same thing! Which is correct, depends on when the conversation happened. Tomorrow is the day after today. The following day is the day after some other point in time. If you just spoke to him today, he said he has to work tomorrow. If the conversation happened further in the past, he said he had to work the following day.

It’s a known problem for learners of English. I have to recheck every time I use indirect speech because it cause against my intuition. Generally the rule is that the indirect speech shifts to the tense relative to the tense if the main clause. I am happy -> I said I _was_ happy. I will be happy -> I said I _would be_ happy (the infamous”future in the past”) I was happy -> I said I _had been_ happy (not even sure about that one) You are never expected to use “I said I am etc” Tbh, I am surprised that native speakers are saying that they don’t understand that form. And you can’t say tomorrow when referring to day in the past - that’s why “the following day”. Could have been”tomorrow” if he said what he said earlier today and I am quoting today and tomorrow that was referred is still in the future.

They're all correct, depending on the context

What is "Question 3"?

The reason D is correct is because his statement was made in the past ("said"), describing the state he was in at that time (having to work). Therefore, him being in that state is also a thing that happened in the past, and needs to be in the past tense: "had to work." You could use "tomorrow" if you were talking about this on the same day that he said it, so that "tomorrow" is both the day after him saying it and the day after you describing him saying it. However, if you're not describing his statement on the same day that he said it, then it needs to be "the following day."