The answers are: B, C and D.
In A, there is no punctuation.
B) Terry practiced her Tae Kwon Do; she wanted to do well in the competition Saturday. The two independent clauses are joined by a semicolon.
In C, An independent clause and a dependent clause are joined by a subortinating conjuction, using a comma.
D) Terry practiced her Tae Kwon Do because she wanted to do well in the competition Saturday. The two independent clauses are joined by a conjunction (because).