**Core Concept**
The hypothalamic-pituitary-gonadal axis regulates reproductive functions in men, with luteinizing hormone (LH) playing a crucial role in stimulating Leydig cells in the testes to produce testosterone.

**Why the Correct Answer is Right**
LH, secreted by the anterior pituitary gland, binds to its receptor on the surface of Leydig cells, triggering a cascade of intracellular signaling pathways that ultimately lead to the production and release of testosterone. This process is essential for spermatogenesis, maintenance of secondary sexual characteristics, and overall male reproductive health. The Leydig cells contain the enzyme cholesterol desmolase, which is involved in the first step of testosterone synthesis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because LH does not directly control secretion of FSH (follicle-stimulating hormone), which is another hormone secreted by the anterior pituitary gland and is primarily involved in spermatogenesis and maintenance of Sertoli cells.
**Option B:** This option is incorrect because LH does not directly control secretion of growth hormone, which is secreted by the anterior pituitary gland and is involved in growth and development, particularly during childhood and adolescence.
**Option C:** This option is incorrect because LH does not directly control secretion of prolactin, which is secreted by the anterior pituitary gland and is involved in lactation and reproductive functions in women.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that LH surge, which occurs in the mid-cycle of the menstrual cycle, is responsible for ovulation and testosterone production in men. This surge is triggered by a feedback mechanism involving estrogen and progesterone levels.

**Correct Answer: C. Testosterone. Testosterone.**