Assertion: Liver is referred to as the primary excretory organ in vertebrates.
Reason: Liver helps kidneys in the secretion of urine.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. if both assertion and reason are true but reason is not the correct explanation of assertion.
C. if assertion is true but reason is false
D. if both assertion and reason are false.

Explanation

### Step-by-Step Solution

1. **Understanding the Assertion**: The assertion states that the liver is referred to as the primary excretory organ in vertebrates. To evaluate this, we need to consider the roles of different organs in excretion.

2. **Identifying the Primary Excretory Organ**: In vertebrates, the primary excretory organ is the kidney. The kidneys are primarily responsible for filtering blood and producing urine, which eliminates waste products from the body.

3. **Evaluating the Role of the Liver**: While the liver does play a significant role in excretion, it is not the primary excretory organ. The liver is involved in the metabolism of substances and the production of urea, which is then excreted by the kidneys. It also excretes bile pigments and cholesterol but does not directly excrete urine.

4. **Understanding the Reason**: The reason states that the liver helps kidneys in the secretion of urine. This is misleading because while the liver produces urea (a component of urine), it does not directly assist the kidneys in the process of urine formation or secretion.

5. **Conclusion**: Since the assertion is incorrect (the liver is not the primary excretory organ; the kidneys are) and the reason is also incorrect (the liver does not help the kidneys in urine secretion), we conclude that both the assertion and reason are false.

6. **Final Answer**: The correct option is the fourth one: both assertion and reason are false.