Answer:
Option A. Korea.
Explanation:
Buddhism was first introduced to Korea from China in the 4th century. During its early spread on the country, buddhism was widely accepted, and it was even broadly supported to become the state ideology during the Goryeo era. It was when the Joseon era saw birth that buddhism suffered repression, as confucianism dominated as the prime ideology.
It is believed that Japanese buddhism spread from Korea began in 577 after a detachment of Korean scholars was sent to Japan by invitation.
