Okay, let's tackle this question about Sertoli cells and the hormone they secrete. First, I need to recall what Sertoli cells are and their functions. They're in the testes, right? Part of the seminiferous tubules. Their main role is to support sperm production, so they probably secrete something related to that.

The hormones I remember associated with the testes include testosterone, but that's from Leydig cells, not Sertoli. Then there's inhibin, which I think is involved in regulating FSH. Oh wait, Sertoli cells produce inhibin. That's it. So the answer should be inhibin. Let me double-check. Inhibin is secreted by Sertoli cells and inhibits FSH secretion from the anterior pituitary. That makes sense because FSH is necessary for spermatogenesis, so when sperm production is sufficient, inhibin would feedback to reduce FSH.

Now, the other options—testosterone is from Leydig cells. AMH (Anti-Müllerian hormone) is also produced by Sertoli cells, but in fetal development. Wait, but the question is about a hormone secreted by Sertoli cells. AMH is present in males to prevent the development of Müllerian ducts. But in adults, Sertoli cells mainly produce inhibin. So maybe AMH is a distractor here. Then there's relaxin, which is more associated with females, but some sources mention it in males too. However, I think relaxin is more from the corpus luteum or placenta. Then maybe testosterone is another option. So the options might be A. Testosterone, B. Inhibin, C. Relaxin, D. AMH. The correct answer would be Inhibin B.

Wait, but AMH is also a hormone from Sertoli cells. So if AMH is an option, why isn't it the answer? Because the question is about the hormone they secrete. Inhibin is the main one related to spermatogenesis feedback. AMH is more about fetal development. So the answer is inhibin. Let me confirm. Yes, Sertoli cells secrete inhibin B, which inhibits FSH. Testosterone is from Leydig cells. AMH is from Sertoli but in fetal life. So in the context of the question, the correct answer is inhibin. The other options are either from different cells or different functions.

**Core Concept**
Sertoli cells in the testes play a critical role in spermatogenesis and hormonal regulation. They secrete **inhibin**, a glycoprotein hormone that negatively regulates follicle-stimulating hormone (FSH) secretion from the anterior pituitary by providing a negative feedback loop.

**Why the Correct Answer is Right**
Inhibin, specifically **inhibin B**, is produced by Sertoli cells in response to FSH stimulation. It binds to receptors in the anterior pituitary, suppressing FSH release. This feedback mechanism ensures that spermatogenesis remains balanced. Inhibin also modulates Sertoli cell function by inhibiting the conversion of testosterone to estradiol, maintaining optimal hormonal conditions for sperm production.

**Why Each Wrong Option is Incorrect**
**Option A:** *Testosterone* is secreted by Leydig cells, not Sert

✓ Correct Answer: B. Inhibin.