C. Enforcing immigration laws.
According to the graph, we can say that <span>
Nigeria was generating greater revenue from oil in 1990 compared to previous years. </span><span>If we look on the table, we can see how the oil industry has covered more of the economy, so if it went down, Nigeria would get in serious economical problems.</span>
<span>A strong economy and proving that the economy was the best.</span>
