Japan's largest and main island, containing the Japanese capital and almost all of its core area is:

a. Kyushu

b. Honshu

c. Shikoku

d. Hokkaido E. Sakhalin

The capital of Japan is Tokyo, it's a big city with 13 million people and almost 40 million people in its surroundings.

Tokyo is located on the island of Honshu - so this is enough to know that the correct answer is b).

Honshu is in fact the biggest Japanese island and it includes the holy Mount Fuji.