Final answer:
Nigeria's economic growth since the 1980s has been mainly driven by its natural resource exports, particularly crude oil, which has been a significant source of revenue. The correct option is C.
Step-by-step explanation:
The factor that has contributed most to Nigeria's strong economic growth since the 1980s is c) Natural resource exports, particularly oil. Nigeria's economy has been significantly bolstered by its oil industry. The export of natural resources such as crude oil has provided Nigeria with the necessary capital to contribute to its economic growth and has been a major source of revenue for the country.
Additionally, this has allowed Nigeria to invest in other sectors such as infrastructure and technology, but the primary stimulant for its economic rise remains its rich oil reserves that have been in high demand globally.