**Core Concept**
Sertoli cells in the testes play a crucial role in the development and maintenance of spermatogenesis. They provide structural and nutritional support to the developing sperm cells, and their secretions are essential for regulating the process.

**Why the Correct Answer is Right**
Sertoli cells secrete Müllerian Inhibiting Hormone (MIH), also known as Anti-Müllerian Hormone (AMH). MIH is a protein hormone that inhibits the development of the Müllerian ducts in male embryos, which would otherwise form the fallopian tubes, uterus, and upper part of the vagina. This hormone is produced by Sertoli cells in response to follicle-stimulating hormone (FSH) from the pituitary gland. The secretion of MIH by Sertoli cells is essential for the normal development of male reproductive organs and the prevention of female reproductive tract development in males.

**Why Each Wrong Option is Incorrect**

**Option A:** Testosterone is produced by Leydig cells, not Sertoli cells, in the testes. Leydig cells are responsible for the production of androgens, including testosterone, which is essential for the development of male characteristics and secondary sex traits.

**Option B:** Dehydroepiandrosterone (DHEA) is a steroid hormone produced by the adrenal glands and the gonads, but it is not secreted by Sertoli cells. DHEA is a precursor to other hormones, including testosterone and estrogen, but it is not directly involved in the regulation of spermatogenesis.

**Option D:** Progesterone is a steroid hormone produced by the ovaries and the placenta, but it is not secreted by Sertoli cells. Progesterone is essential for the maintenance of pregnancy and the development of the embryo, but it is not involved in the regulation of spermatogenesis.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that Sertoli cells play a crucial role in the regulation of spermatogenesis, and their secretions, including MIH, are essential for the normal development of male reproductive organs. Sertoli cells are also involved in the regulation of the immune response in the testes and the prevention of autoimmune diseases.

**✓ Correct Answer: C. MIH**