Option 1 -> (A)-(I) "event which closes soon" is incorrect; events happen, they don't close. (B)-(II) "before it would have gone" is wrong tense for this context.
Option 2 -> (A)-(IV) "event which will happen soon" ✓; (B)-(I) "before it closes" ✓; (C)-(II) "he would have gone to bed" ✓; (D)-(III) "are going to be available" ✓. All match grammatically and contextually.
Option 3 -> (A)-(I) "event which closes soon" is incorrect; (C)-(IV) "he will happen to bed" is nonsensical.
Option 4 -> (A)-(III) "event which are going soon" has subject-verb disagreement; (B)-(IV) "before it will happen" doesn't fit the post office context.
Hence, Option 2 -> Sentence (A) needs future tense for an upcoming event ("will happen"), (B) requires present tense for routine closing time ("closes"), (C) needs modal perfect to express probability about a past action ("would have gone"), and (D) requires near future construction for forthcoming books ("are going to be") -> correct