Task: Question Answering
Input (English): Which statement describes how muscles work to allow a person to extend an arm from a curled position by straightening the elbow?  
 (A) Both the biceps and triceps contract. (B) Both the biceps and the triceps relax. (C) The triceps contract and the biceps relax. (D) The biceps contract and the triceps relax.
Output (English): C