Exertion of potassium is governed primarily by

Options

A. Potassium reabsorption in proximal convoluted tubule
B. potassium secretion in proximal convoluted tubule
C. potassium secretion in distal convoluted tubule
D. potassium reabsorption in distal convoluted tubule.

Explanation

To solve the question regarding the primary regulation of potassium excretion, we can follow these steps:

### Step 1: Understand Potassium Excretion
Potassium excretion primarily occurs in the kidneys, where it is filtered and either reabsorbed or secreted based on the body's needs.

### Step 2: Identify the Key Locations in the Kidney
The kidneys consist of several parts, including the proximal convoluted tubule (PCT) and the distal convoluted tubule (DCT). Each of these segments has different roles in the handling of potassium.

### Step 3: Analyze the Role of the Proximal Convoluted Tubule
The proximal convoluted tubule is responsible for reabsorbing a significant portion of filtered potassium. Approximately 66% of potassium is reabsorbed here, which means that it does not contribute significantly to potassium excretion.

### Step 4: Examine the Distal Convoluted Tubule
The distal convoluted tubule is where potassium secretion occurs, especially under the influence of the hormone aldosterone. When potassium intake is high, aldosterone promotes the secretion of excess potassium into the filtrate, leading to increased excretion.

### Step 5: Conclusion
Based on the above analysis, the primary regulation of potassium excretion is governed by potassium secretion in the distal convoluted tubule, particularly influenced by aldosterone.

### Final Answer
The correct answer is **potassium secretion in the distal convoluted tubule** (Option C).

---