The flexor carpi ulnaris is a muscle that adducts and flexes the hand at the wrist. The muscle attaches to both the humerus and the base of the 5th metacarpal. Based on the movement that this muscle performs, which attachment is the origin?

• A. Humerus.
• B. Wrist.
• C. 5th metacarpal.
• D. It's impossible to say from the information given.