Assertion : Catalytic converters must be used in cars.
Reason : Catalytic converter helps to reduce the formation of acid rain.

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 c orrect explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To analyze the given statements regarding catalytic converters and their role in reducing air pollution and acid rain, we can break down the solution into the following steps:

### Step 1: Understand the Assertion
The assertion states that "catalytic converters must be used in cars."
- Catalytic converters are essential components in modern vehicles that help reduce harmful emissions from the exhaust. They convert toxic gases like carbon monoxide, hydrocarbons, and nitrogen oxides into less harmful substances before they are released into the atmosphere.

### Step 2: Evaluate the Reason
The reason provided is that "catalytic converters help to reduce the formation of acid rain."
- Acid rain is primarily caused by the release of sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere, which can come from vehicle emissions. Catalytic converters play a crucial role in reducing these emissions, thus indirectly helping to mitigate the formation of acid rain.

### Step 3: Analyze the Relationship Between Assertion and Reason
- The assertion is true because catalytic converters are indeed necessary for reducing harmful emissions from cars.
- The reason is also true because by reducing the emissions of NOx and SO2, catalytic converters contribute to lowering the potential for acid rain formation.

### Step 4: Determine if the Reason Explains the Assertion
- The reason provided does explain the assertion. Since catalytic converters reduce the emissions that contribute to acid rain, they are essential for both reducing air pollution and preventing acid rain.

### Conclusion
Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both the assertion and reason are true, and the reason is a correct explanation of the assertion.