Which is true regarding rennin secretion?

Options

A. Directly proportional to the ADH levels
B. Decreased `Na^(+)` in DCT increases rennin secretion
C. Increased `K^(+)` in PCT increases renin secretion
D. Inversely proportional to the potassium levels

Answer

### Step-by-Step Solution:

1. **Understanding Renin Secretion**: Renin is an enzyme secreted by the juxtaglomerular cells located in the afferent and efferent arterioles of the kidneys.

2. **Role of Macula Densa**: The macula densa is a group of specialized cells located in the distal convoluted tubule (DCT) that is sensitive to sodium chloride (NaCl) concentration.

3. **Sodium Chloride Sensitivity**: When the concentration of sodium chloride decreases in the DCT, the macula densa detects this change.

4. **Response to Decreased Na+**: In response to lower Na+ levels, the macula densa signals the juxtaglomerular cells to increase the secretion of renin.

5. **Conclusion**: Therefore, the statement that is true regarding renin secretion is: "Decreased Na+ in DCT increases renin secretion."

### Final Answer:
Decreased Na+ in DCT increases renin secretion.

---