`ul((A))` acts at the leyding cells and stimulates synthesis and secretion of `ul((B))`.

Answer

To solve the question, we need to identify the hormones involved in the process of spermatogenesis and their respective actions on specific cells in the male reproductive system.

### Step-by-Step Solution:

1. **Identify the Hormones**: The question refers to a hormone that acts on Leydig cells. In the male reproductive system, the two key hormones involved are Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH).

2. **Action of LH**: Luteinizing Hormone (LH) specifically acts on Leydig cells, which are located in the testes.

3. **Function of Leydig Cells**: When stimulated by LH, Leydig cells synthesize and secrete androgens, which are male sex hormones. The primary androgen produced is testosterone.

4. **Conclusion**: Therefore, the answer to the question is:
- (A) LH acts at the Leydig cells and stimulates the synthesis and secretion of (B) androgens (testosterone).

### Final Answer:
(A) LH acts at the Leydig cells and stimulates the synthesis and secretion of (B) androgens.

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