Answer:
European populations grew as a result of American foods being introduced to European diets.
Explanation:
Answer: D is right. But there are also many other reasons.
Explanation: League of Nations was formed by Allied powers (from the WW I) so consequently it was viewed as "League of Victors". Moreover USA did not join, may other states did not join and later on League of Nations was unable the prevent outbreak of WW II.
Sea explorations were made by many countries centuries ago. These were headed by the European countries long back. The impulses or urges that influenced the explorers are to desire to take hold of other land for territorial expansion.
Another very important thing to consider as well was the trading. One country had to exchange products to another country. Hence, there were need for them to cross the seas.