Assertion (A): Northern plains of India receive some rainfall in winter. Reason (R): North-East Monsoon is active in win
In Assertion-Reason, check both parts calmly. Here, the combination that fits is Both (A) and (R) are true, but (R).... In Winter Rainfall, this is how Assertion and Reason are linked. If you check Assertion first, then Reason, then the link, the answer becomes clear. That is the simple way to do it.
Ref: [Karnataka PSC (Pre) 2017 UPPCS (Pre) 1998] | Majid Husain, Geography of India, and NCERT Geography textbooks discuss Winter Rainfall and explain the Indian geographical features and patterns that support the correct answer for this question.