In which sentence is the comma correctly placed? Quickly, finish your homework before dinner., After he finished his meal, he went out., She sings, and dances gracefully., I tried to help him but, he refused.

Quickly, finish your homework before dinner.

After he finished his meal, he went out.

She sings, and dances gracefully.

None of these

After he finished his meal, he went out.

The comma separates the introductory dependent clause ("After he finished his meal") from the independent clause ("he went out").