While all the options presented can have a positive impact on Nigeria's economy, the capital investment that would MOST benefit Nigeria’s economy is C. adult literacy programs.
Investing in adult literacy programs can significantly enhance the workforce's skills, increase employability, improve productivity, and contribute to poverty reduction. A more literate population can also drive innovation, entrepreneurship, and overall economic growth, which can have lasting effects on the economy.
While industrial equipment investments (options A and B) can enhance specific sectors, they might not address the broader, underlying issue of human capital development as effectively as education initiatives. Option D, universal higher education, is also important but may require more time to show economic benefits compared to adult literacy programs. Therefore, investing in adult literacy programs may provide a quicker and more widespread boost to Nigeria's economy.