The correct answer is c) They used violence against Japanese bureucrats.
In 1919, after years of war, Korea was annexed by the Empire of Japan, that lasted until 1945. The Empire of Japan tried to erase Korean culture by forbidding the usage of Korean language or teaching only "approved" history, wiping historical memory of Korea. They also took control of their labor and land, planting Japanese trees for example.
In responce, some Korean resistance groups were formed in Manchuria, they were known as the Dongnipgun or Liberation Army. They carried out guerrilla attacks against japanese forces. These groups were constantly constrained but never destroyed at all. Other Koreans had their own ways of pacifically rebeling like refusing to speak japanese,
