What was one economic effect of the Spanish-American War? Select one:
A-The United States gained direct access to additional natural resources
and overseas markets
B-Shipbuilding industries in the United States declined
C-New free and fair trade treaties were established between the United
States and developing countries
D-Demand for coal and petroleum as energy sources declined

A-The United States gained direct access to additional natural resources and overseas markets.

Explanation:

The Spanish-American War was a conflict that occurred between Spain and the United States of America from the 21st of April, 1898 to the 13th of August, 1898. The conflict started in Cuba as a result of the internal explosion of U.S.S Maine (Navy ship) located at the Havana Harbor. Consequently, the United States of America intervened in support of Cuba during their war for independence. USA was victorious and consequently took possession of Spanish Philippines and Guam.

One economic effect of the Spanish-American War was that, the United States gained direct access to additional natural resources and overseas markets.

I don't know of any events in Greece at the time, so I think we can reject this answer.

HUngary is correct, except that it was not independent at the time, but part of the Austrian Empire, so it's already included in the question.

Spain had a little unrest, but not a lot.

The best answer is Italy - it had very important events during this time, for example the revolution in Sicily in 1848.