Final answer:
The question pertains to identifying a mesomorph according to William H. Sheldon's theory; however, given the provided descriptions, it cannot be determined as none mention physical traits or competitive behavior characteristic of mesomorphs.
Step-by-step explanation:
According to William H. Sheldon's theory, a mesomorph is characterized by a muscular and well-built body, a high metabolism, and good posture. The theory suggests that mesomorphs are assertive, vigorous, and have a competitive nature. Considering the provided sentences, none of them directly describe physical traits or behaviors that can conclusively identify a mesomorph. Therefore, the correct answer is: 4) Cannot be determined from the given descriptions.