Assertion : The joint present between bones of the upper arm and fore arm is pivot joint.
Reason : Pivot joint allows all-round movement.

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 joint present between bones of the upper arm and forearm is a pivot joint."
- To evaluate this, we need to identify the joint between the upper arm (humerus) and the forearm (radius and ulna). This joint is actually a hinge joint, which allows movement primarily in one direction (flexion and extension).

2. **Understanding the Reason**: The reason provided is "Pivot joint allows all-round movement."
- A pivot joint does allow for rotational movement, but it does not provide all-round movement. The type of joint that allows for all-round movement is the ball-and-socket joint (like the shoulder joint).

3. **Evaluating Both Statements**:
- Since the assertion is incorrect (the joint is a hinge joint, not a pivot joint) and the reason is also incorrect (a pivot joint does not allow all-round movement), we conclude that both statements are false.

4. **Choosing the Correct Option**:
- Based on the evaluation, since both the assertion and the reason are false, the correct option is D: "If both assertion and reason are false."