Given below are two statements, one is labelled asAssertion (A) :and the other as Reason (R).Assertion (A):Jet streams discovered during World War II are high altitude easterly winds.Reason (R):Jet streams flow with a speed of 300-500 km/ hour.Select the correct answer from the codes given below:

1. A

   Both (A) and (R) are true and (R) is the correct explanation of (A).

   Option (a) claims both the assertion and reason are true and (R) explains (A). This is incorrect because the assertion itself contains a factual error regarding the wind direction.

2. B

   (A) is false, but (R) is true.

   Option (b) claims that Assertion (A) is false, but Reason (R) is true. Jet streams are actually high-altitude westerly winds, making the assertion false, while their recorded speed of 300 to 500 kilometres per hour during peak conditions is indeed accurate and well-documented in meteorological studies.

3. C

   Both (A) and (R) are true, but (R) is not the correct explanation of (A).

   Option (c) claims both statements are true but denies the explanation link. This fails because the assertion states an incorrect fact about the direction of the jet streams.

4. D

   (A) is true, but (R) is false.

   Option (d) claims the assertion is true and the reason is false. This is the exact opposite of the meteorological reality, as jet streams are westerly winds and their speed figures are accurate.

Summary. Official key is (b) because the assertion wrongly characterizes jet streams as easterly winds instead of westerly winds, rendering (A) false. Meanwhile, the reason correctly states their high operational speed range of 300 to 500 kilometres per hour, making (R) true. Students often confuse upper-air circulation directions with surface trade winds. Therefore, only option (b) accurately reflects the independent validity of the reason while rejecting the false assertion.