This sentence is inverted.

The subject is what is filled in the back line, and it is also the adverbial referred to there. The predicate is be.

In general English, the subject form of verbs is expressed in the form of "to+ verb" or "verb present participle"

So in order to fill in a qualified subject on the horizontal line, B was excluded.

Wake up is a phrasal verb (verb+adverb), which means to wake someone up. So rule out C.

You is a pronoun, so it can only be placed between wake and up, so D is excluded. Some woke me up, too. Give up. I, it, you are pronouns, and you should be placed in the middle of this adverb (verb+adverb). But if it is a name, or a specific thing, such as waking Jane up, or giving up the game, it should be placed after this adverb.

So you can only choose a.

Come on!