Assertion : If you are facing North and turn anti-clockwise to face west, you make `(3)/(4)` of a revolution.
Reason: Turning by two straight angles in same direction makes a full turn i.e., one revolution.

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 assertion is false but reason is true.

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states: "If you are facing North and turn anti-clockwise to face West, you make \( \frac{3}{4} \) of a revolution."

- When you are facing North and turn anti-clockwise to face West, you move from North to West.
- The directions can be visualized as follows:
- North (0 degrees)
- West (270 degrees)

To determine how much of a revolution this is:
- A full revolution is \( 360 \) degrees.
- Turning from North (0 degrees) to West (270 degrees) is a \( 90 \) degree turn.

Now, to find out what fraction of a revolution this is:
\[ \text{Fraction of revolution} = \frac{\text{Degrees turned}}{\text{Total degrees in a revolution}} = \frac{90}{360} = \frac{1}{4} \]

Thus, the assertion is **false** because turning from North to West is \( \frac{1}{4} \) of a revolution, not \( \frac{3}{4} \).

### Step 2: Understand the Reason
The reason states: "Turning by two straight angles in the same direction makes a full turn, i.e., one revolution."

- A straight angle is \( 180 \) degrees.
- Therefore, two straight angles equal \( 180 \times 2 = 360 \) degrees, which is indeed a full revolution.

This statement is **true**.

### Conclusion
- The assertion is false, and the reason is true.
- Therefore, the correct option is: "Assertion is false but reason is true."