What economic problems led to nigerias adoption of military rule in the 1980s

The answer is prolonged drought.
In October 1979, after more than 13 years of military rule, Nigeria was returned to democratic rule. The National Party of Nigeria emerged victorious in the presidential election and Alhaji Shehu Aliyu Shagari was elected the first Executive President. It was not to last. The hunger and poverty that characterized the last days of the Second Republic prompted the Armed Forces to take power in December 1983. 

C.about 10% i think