Assertion: Projectile motion is uniformly accelerated motion. (Neglect the effect of air. )
Reason: In projectile motion, speed remains constant.

Options

A. If both assertion `&` Reason are True `&` the Reason is a corrrect explanation of the Asserion.
B. If both Assertion `&` Reason are True but Reason is not correct explanation of the Assertion.
C. If Assertion is Trie but the Reason is False.
D. If both Assertion `&` Reason are false

Answer

To analyze the assertion and reason provided in the question, we will break down the concepts of projectile motion and the statements made.

### Step-by-Step Solution:

1. **Understanding Projectile Motion**:
- Projectile motion refers to the motion of an object that is thrown into the air and is subject to the force of gravity. It has both horizontal and vertical components.

2. **Assertion Analysis**:
- The assertion states that "Projectile motion is uniformly accelerated motion."
- This is true because, in projectile motion, the only acceleration acting on the object is due to gravity, which is constant (approximately \(9.81 \, m/s^2\) downward). Therefore, the motion is uniformly accelerated in the vertical direction.

3. **Reason Analysis**:
- The reason states that "In projectile motion, speed remains constant."
- This statement is false. While the horizontal component of velocity remains constant (assuming no air resistance), the vertical component of velocity changes due to the acceleration caused by gravity. Therefore, the overall speed of the projectile does not remain constant throughout its flight.

4. **Conclusion**:
- Since the assertion is true and the reason is false, we conclude that the correct answer is that the assertion is true, but the reason is false.

### Final Answer:
- **Assertion**: True
- **Reason**: False