West Bengal is bounded on the north by:-

West Bengal is a state in eastern India with distinct geographical boundaries. To the north, it shares borders with two specific Himalayan regions: Sikkim and Bhutan. This northern boundary is formed by the eastern Himalayas, separating West Bengal from these neighboring countries and states. Option A correctly identifies Sikkim to the northeast and Bhutan to the north, which aligns with the actual geographical layout of the region.\nOption B is incorrect because Assam lies to the east, not directly north, and Bangladesh borders the south and west sides of West Bengal. Option C is wrong as the Bay of Bengal lies to the southeast, forming a coastline rather than a northern boundary. Option D is incorrect because while Bihar borders West Bengal to the northwest, Nepal does not share a direct border with West Bengal; it is separated by Sikkim and Bhutan. Therefore, the accurate northern boundary consists of Sikkim and Bhutan.