I think it is b because there are key word s like ought
A. European nations competed for land, trade, and military power.
Explanation: Industrialization and the emergence of bigger and stronger nations had caused competition between each other. The German and Italian Empire were recently established, as for the British and French were old empires with vast amounts of colonies. Austria-Hungary was already unstable and threatened small states in the Balkans which the Russian Empire backed them.
Heredity is the passing of traits though genes from parents to their offspring.
It escalated when North Korea Invaded South Korea, When the UN became involved in the conflict to stop war, and also when the US sent in troops and medical units to support South Korea.
So, D
Since 1949, U.S.-China relations have evolved from tense standoffs to a The Chinese embassy in Belgrade after being hit by NATO missiles. calls on China to serve as a “responsible stakeholder” and use its influence to says China's military buildup is “not consistent” with the country's stated goal of a “peaceful rise.