[A] : Amniotic fluid serves as a protective cushion.
[R]: It breaks the mechanical shocks and lessens the effect of changes of temperature.

Options

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

Answer

To solve the question regarding the assertion and reason about amniotic fluid, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Amniotic fluid serves as a protective cushion."
- This means that the amniotic fluid has a protective role for the fetus during pregnancy.

**Hint**: Think about the role of fluids in providing support and protection in biological systems.

2. **Understanding the Reason**:
- The reason given is "It breaks the mechanical shocks and lessens the effect of changes of temperature."
- This suggests that the amniotic fluid not only cushions the fetus from physical impacts but also helps maintain a stable temperature.

**Hint**: Consider how cushioning materials work in real life and how they protect against impacts and temperature changes.

3. **Evaluating the Functions of Amniotic Fluid**:
- Amniotic fluid surrounds the fetus and acts as a cushion, preventing pressure on the umbilical cord and protecting the fetus from external injuries and sudden movements.
- It also helps maintain a constant temperature around the fetus, preventing heat loss.

**Hint**: Reflect on the various protective mechanisms in the body and how they relate to the functions of amniotic fluid.

4. **Determining the Truth of the Statements**:
- Both the assertion and the reason are true based on the functions of amniotic fluid.
- The reason provided accurately explains why the assertion is true, as the cushioning effect is due to its ability to absorb shocks and maintain temperature.

**Hint**: Analyze if the reason logically supports the assertion.

5. **Choosing the Correct Option**:
- Since both the assertion and reason are true, and the reason correctly explains the assertion, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation.

**Hint**: Look for options that state both statements are true and that the reason supports the assertion.

### Final Answer:
The correct option is: **Both assertion and reason are true, and the reason is the correct explanation.**