The correct answer is: C. Wet temperate zone
The wet temperate zone of Himachal Pradesh receives the highest rainfall. The average annual rainfall in this zone is about 2,000 mm. The rainfall is caused by the western disturbances, which are a type of low-pressure system that originates in the Mediterranean Sea. The western disturbances bring moisture-laden winds from the Arabian Sea and the Bay of Bengal. These winds are forced to rise over the Himalayas, which causes them to cool and release their moisture.
The wet temperate zone is located in the southern part of Himachal Pradesh. The climate in this zone is mild and pleasant. The summers are cool and the winters are cold. The vegetation in this zone is mostly deciduous forest.
The other options are incorrect because they do not receive as much rainfall as the wet temperate zone. The humid sub-tropical zone receives an average annual rainfall of about 1,500 mm. The humid temperate zone receives an average annual rainfall of about 1,000 mm. The sub-humid sub-tropical zone receives an average annual rainfall of about 750 mm.