Step 1: Understanding the Question:
• The question gives an Assertion (A) about the first tractor and a Reason (R) about DDT and BHC insecticides.
Step 2: Detailed Explanation:
• As per the NTA final answer key, both statements are treated as correct facts about agricultural history.
• The development of the tractor (farm mechanisation) and the discovery of DDT and BHC (plant protection) are separate developments, so (R) does not explain (A).
Step 3: Final Answer:
The correct option is (B) Both (A) and (R) are correct but (R) is not the correct explanation of (A).