**Core Concept**
Inhibin is a protein complex secreted by the Sertoli cells in the testes and the granulosa cells in the ovaries. It plays a crucial role in regulating the production of follicle-stimulating hormone (FSH) by the pituitary gland. Inhibin has a negative feedback effect on FSH secretion, thereby influencing reproductive hormone balance.

**Why the Correct Answer is Right**
Inhibin is a dimeric protein composed of an alpha subunit and a beta subunit (inhibin A or inhibin B). The alpha subunit is shared with activin, another protein complex that stimulates FSH production. Inhibin binds to its receptor, inhibin/activin membrane-bound serine protease (IAMPS), which activates the SMAD signaling pathway, ultimately leading to the suppression of FSH gene transcription. This regulatory mechanism is essential for maintaining reproductive homeostasis.

**Why Each Wrong Option is Incorrect**
* **Option A:** Inhibin does indeed inhibit FSH production, making this statement true.
* **Option B:** Inhibin is produced by Sertoli cells in the testes and granulosa cells in the ovaries, so this statement is also true.
* **Option C:** Inhibin has a negative feedback effect on FSH secretion, which is a critical mechanism for regulating reproductive hormone balance, making this statement true as well.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that inhibin levels are used as a marker for ovarian reserve in females. Low inhibin B levels are associated with decreased ovarian function and are often seen in women with polycystic ovary syndrome (PCOS) or premature ovarian failure.

**Correct Answer: D.**