Assertion: A rocket moves forward by pushing the surrounding air backwards.
Reason: It derives the necessary thrust to move forward according to Newton's third law of motion.

Options

A. (a) If both Assertion and Reason are true and the Reason is correct explanation of the Assertion.
B. (b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
C. (c) If Assertion is true, but the Reason is false.
D. (d) If Assertion is false but the Reason is true.

Explanation

To solve the assertion-reason question, we will analyze both the assertion and the reason step by step.

### Step 1: Analyze the Assertion
The assertion states: "A rocket moves forward by pushing the surrounding air backwards."

- **Explanation**: This statement implies that the rocket's forward motion is due to the action of pushing the air around it. However, this is not entirely accurate. Rockets do not primarily rely on pushing surrounding air to move forward; they expel gases from their engines.

**Hint**: Consider how rockets operate in space versus in the atmosphere. What do they expel to generate thrust?

### Step 2: Analyze the Reason
The reason states: "It derives the necessary thrust to move forward according to Newton's third law of motion."

- **Explanation**: According to Newton's third law, for every action, there is an equal and opposite reaction. When a rocket expels gas (from burning fuel) downwards, the reaction force pushes the rocket upwards. This is the correct explanation of how rockets generate thrust.

**Hint**: Think about the relationship between action and reaction forces. How does this apply to the motion of a rocket?

### Step 3: Conclusion
Now that we have analyzed both the assertion and the reason:

- The assertion is **false** because it incorrectly states that the rocket moves by pushing surrounding air.
- The reason is **true** because it correctly describes the principle of thrust generation based on Newton's third law.

Thus, the correct answer is that the assertion is false, but the reason is true.

**Final Answer**: Assertion is false, Reason is true.