Jeff is 13 years old and he has recently noticed some remarkable changes in himself. Over the past few months his voice has started to change, growing deeper. He has begun to grow pubic hair, as well as the beginnings of a facial beard. He is also filling out, with his muscles developing rapidly. These changes in Jeff are probably due to the action of . a. gonads

b. thyroid gland

c. pineal gland

d. adrenal gland

Gonads

Explanation:

Gonads are referred to as sex organs (male and female sex organs). The female gonad is called the ovary which is responsible for the production of egg cells, while the male gonad which is the testes, is responsible for sperm cell production. In general, gonads are responsible for producing steroid hormones (sex hormones) in both males and females.

In males, the testes produce sex hormones called androgens. One major androgen produced by the testes is called testosterone. This sex hormone is responsible for changes in the sexual development of males, as well as their appearance. The secretion of testosterone by the male gonad can result in voice changes in males, growth of pubic hair, elevated sexual drive and increased growth in the muscle and skeletal system.

Therefore, the changes observed in Jeff are probably due to the action of gonads.

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