The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
The city's yearly rainfall average stands at 11,777 millimetres (463.7 in). The reason, lying on the windward side of the Khasi hills, Cherrapunji in Shillong receives the southwest monsoons caused by the orographic lift which increases the precipitation levels. Further, the Himalayas form a barrier for the monsoon winds and prevents them from traveling north thereby bringing in heavy rainfall in the Terai region and Brahmaputra valley. This brings in the north east monsoons for Cherrapunji.