Which system influences secondary sexual traits through reproductive function?

• A. Reproductive System
• B. Endocrine System
• C. Circulatory System
• D. Urinary System

Answer: (A)

Secondary sexual traits come from hormones produced by the gonads as part of reproduction. The ovaries and testes release sex hormones (estrogen and testosterone) that drive puberty and the development of sex-specific features such as body hair, voice changes, fat distribution, and breast development. Because these traits arise from the reproductive organs themselves and their hormonal activity related to reproduction, the reproductive system is the system that most directly influences secondary sexual characteristics. The circulatory system mainly transports hormones, and the endocrine system regulates many processes, but the direct source shaping these particular traits is the reproductive system.