Concept:The rapid spread of Christianity in Nigeria is mainly linked to Western education.
Explanation:After Britain abolished the slave trade in 1833, many freed Africans were resettled in Sierra Leone.
Some of them later traced their roots back to Nigeria.
These returnees and other converts received education from the Church Missionary Society (CMS).
Western education enabled many Nigerians to read and understand the Bible.
It also produced educated African evangelists who carried Christianity to different communities.
Answer:The fast spread of Christianity in Nigeria is associated with Western education.
Therefore, the correct option is D. western education.