Please help me this is my final exam and i dont want to fail. Which sentence uses a comma and a coordinating conjunction correctly to separate two independent clauses?

A. To be honest, I always thought you'd be better at playing goalie.

B It looks as if it might rain, so I brought two umbrellas for us to use.

C. We can do our homework together or, you can just come over when you're done.

D. Staying alert, and making good decisions are part of being a responsible babysitter.