Option 1 -> "put off" doesn't fit "drop off letters"; "put up" doesn't mean casual visit; incorrect matching.
Option 2 -> "drop by" doesn't fit delivering letters; "drop off" doesn't mean casual visit; incorrect matching.
Option 3 -> "drop off" (deliver letters), "drop by" (casual visit), "put up" (accommodate), "put off" (annoyed/discouraged); all correctly matched.
Option 4 -> "put up" doesn't fit delivering letters; "put up" repeated for B; "drop by" doesn't fit being annoyed; incorrect.
Hence, Option 3: (A) - (III), (B) - (IV), (C) - (I), (D) - (II) -> "drop off" means to deliver/leave something at a place; "drop by" means to visit casually; "put up" means to accommodate someone; "put off" means to be discouraged or annoyed by something -> correct