It meant that as soon as one country falls under communist control, another country would fall and so on. Vietnam at the time was split into North (communist) and South (being attacked by North) and the US didn't want communism to spread, reasoning that it might eventually come to the US if nothing was done.
The correct answer is increase.
Government subsidies make it easier or more beneficial to provide the goods that the producers are offering (or to consume more), so the subsidized parties will produce more of their products, which will increase the supply.
The answer is: A - In order to make money in Pacific territories and nations.
Cortes was interested in converting natives to Christianity