What is the best word for this sentence?

This was prolly made by someone who is not a native speaker. I would think A, B and C are possible, but sound weird.

While you wouldn’t use “for” on it’s own here, you could use “up for”. “I’m not really up for going out tonight. I’d rather stay home and relax.”

A is the best answer. D would work with a “but.” I’m not really against going out tonight, but I’d rather stay home… B works, too, but does not strike me as as common as A. To be “for” something means to support it.

Definitely not d. If you're against something, it means you don't want it. "I'm not against going out" means you don't mind doing it. (It can mean that you want to, but more often it means you don't really care one way or the other. It's kind of a complicated social thing.) The rest of the sentence indicates that the speaker wants to stay home, so they are against going out. Into, for, and about actually all work in this case and I'm not completely sure which your test wants. Being "into something" means being interested or being a fan of it. You can say "I'm into the idea of pizza for dinner" or "I'm not into jazz music". It's kind of informal conversational slang though and not something your teacher probably has you learning. Being "for something" means that you support it. It's usually used specifically for ideas or plans in this usage. You can be "for workers rights" or "for the new road construction" or if someone asks if you want pizza for dinner you can reply "I'm for it!" It comes across kind of formal and stilted in conversations. In the last example, it's a slightly silly jokey way to reply because it mixes formality. This is actually my guess for the correct answer because the opposite of for in this sense is against and the fact that the question includes both feels like a clue. Being "about something" means that it's an ongoing interest for you. "I'm all about pizza" means you want pizza frequently. This is not the most common use of "about" but not at all unusual. Think of the song, "I'm all about that bass." Tldr, Bad question.

They all make sense besides D, which is saying that you are not opposed to going out

I would not use "against" unless the sentence read "I'm not really against going out tonight but I'd rather stay home and relax" Into is the best option here but I am not sure I would use that in a casual conversation maybe I would use something like "I'm not really feeling like going out tonight"

I would answer 'for' as an antonym of 'against', but in a real conversation, I'd opt for rephrasing it some other way, e.g. 'I'm not willing to go out tonight' or along the lines edit: grammar brainfart removal

against.

Depends upon what you want to convey. "Into" and "for" both convey you do not want to go out, whereas "against" conveys you are okay with going out. "About" does not make sense.

I would use 'for'.

"D" is the only one which is actually wrong, but the other three are different degrees of informal, and different subcultural slang. "I'm not really about going out tonight" is perhaps the least likely, even though it's something I might say. I think the most typical one, the one which I would suspect would be the intended answer, would be "I'm not really for going out tonight." But I would personally use A, B, or C.

In a actual conversation people would understand all 4

D would have the opposite meaning - i.e. I want to go out tonight.