Choose A, B, C, or D to indicate the sentence which is the most correct. When / their mother / came home / 10 o'clock last night, / they / not study; / they / chat.

When their mother comes home at 10 o’clock last night, they weren’t studying; they were chatting.

When their mother came home at 10 o’clock last night, they weren’t studying; they were chatting.

When their mother came home at 10 o’clock last night, they didn’t study; they chatted.

When their mother was coming home at 10 o’clock last night, they weren’t study; they were chatting.