The correct answer is: Both A and R are true and R is the correct explanation of A.
Assertion (A) states that some roads in Himachal Pradesh are closed during winters. Reason (R) states that snowfall and landslides are major problems in these areas.
Both A and R are true. Snowfall and landslides are common in Himachal Pradesh during winters, and these events can damage roads and make them impassable. As a result, some roads in Himachal Pradesh are closed during winters.
R is the correct explanation of A. The reason why some roads in Himachal Pradesh are closed during winters is because of snowfall and landslides.
The other options are incorrect. Option B is incorrect because R is not the correct explanation of A. Option C is incorrect because A is true, but R is false. Option D is incorrect because A is false, but R is true.