4. Choose the sentence that expresses the thought most clearly and effectively and that has no errors in structure.
A) Playing tennis helps a teenager gain poise, learn to be coordinated, and build strength.
B) Playing tennis helps a teenager gain poise, learn coordination, and build strength.
C) Playing tennis helps a teenager to gain poise, learn to be coordinated, and for building strength.
Choice B contains a parallel structure. The other choices lack parallelism, and are unnecessarily wordy.