**Core Concept**
The testes contain two main types of cells: germ cells, which give rise to sperm, and somatic cells, which provide structural and functional support to the germ cells. Sertoli cells and Leydig cells are the two types of somatic cells found in the testes, each playing distinct roles in spermatogenesis and testosterone production.

**Why the Correct Answer is Right**
Sertoli cells are essential for the development and maturation of sperm cells. They provide nutrients, support, and protection to the developing sperm and play a crucial role in the regulation of spermatogenesis. Sertoli cells also produce androgen-binding protein, which binds to testosterone, maintaining high levels of testosterone in the seminiferous tubules. This allows for the proper development and maturation of sperm cells.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a correct answer because Sertoli cells are not the primary source of testosterone production in the testes. That role is performed by Leydig cells.
**Option B:** This option is not a correct answer because while Leydig cells do interact with Sertoli cells, they are not the supporting cells of the testes.
**Option C:** This option is not a correct answer because peritubular cells are a type of cell found in the testes, but they are not the primary supporting cells of the testes.

**Clinical Pearl / High-Yield Fact**
Sertoli cells are essential for the proper development and maturation of sperm cells, and their dysfunction can lead to impaired spermatogenesis and infertility.

**Correct Answer: C. Sertoli cells. Sertoli cells are the supporting cells of the testes, playing a crucial role in spermatogenesis and testosterone regulation.**