Around 1900, european nations built up the military forces, formed alliances, and expanded there colonial holdings in effort to a. force their enemies to start wars b. maintain a balance of power c. put a conscription system in place d. end the spirit of militarism

The answer is b.  to over power other enemy countries

The correct answer is “maintaining a balance of power.” (B). This decision was made based on how the other countries were behaving, they raised their anger. The European nations started investing in their defense, consequently the accumulation of weaponry was real, doubling its amount by 1890-1930. This gave them the chance to show their power, create the spirit of nationalism among the citizens and avoid any chance of revolution inside the country.

"choosing is refusing" means individuals face an opportunity cost with each decision they make. economists state that every decision involves trade-offs. opportunity cost is the least desirable alternative given up as a result of a decision.