A. the sole source of the nation's revenue B. the oldest industry in the country C. the mainstay of the economy D. a factor in the decline in the nation's foreign reserves
Correct Answer: D
Explanation
The petroleum industry in Nigeria is the largest on the African continent. As of 2014, Nigeria's petroleum industry contributes about 14% to its economy. Therefore, though the petroleum sector is important, it remains in fact a small part of the country's overall diversified economy
