How do I tell the difference between a DEPENDENT CLAUSE and a phrase?

Which sentence combines the two ideas by using a complex sentence?

A. Before the rain ended, we splashed in the puddles B. Before splashing in the puddles, we put on our boots C. Before the storm, we played outside.

Barking loudly during the night, my dog chased away an intruder. B. Because my dog barked loudly during the night, the intruder ran away. C. While barking loudly, my dog chased an intruder last night.

A. After running the half marathon, we needed a rest. B. After we ran the half marathon, we needed a rest. C. After the half marathon, we needed a rest.

KEY: A , B, B If you were absent, see me during homeroom for an explanation.