The correct answer is - A. Islamic; Christian.
The West African country of Nigeria is a territory where the people were heavily influenced by both, Muslim, and Christian missionaries. In general, the local population was not looking very fondly to the new missionaries at first, and were not willing to change their native religions. But as the time was passing, the influence was getting bigger, and very often the natives were forced to accept some of this religions, thus becoming a country where two foreign religions became the dominant among the majority of the population.
According to the statistics, around 50% of the population in Nigeria is practicing Islam, and around 40% is practicing the Christian faith, while the rest of the population is still practicing some of the multiple native religions.
