Final answer:
A firm must consider the wealth of customers, living standards, and economic growth when entering foreign markets to ensure long-term success. Therefore, the correct option is A.
Step-by-step explanation:
When choosing which foreign markets to enter, a firm must consider a variety of factors, including the wealth of customers, living standards, and economic growth of the potential markets. Economic growth is particularly important as it provides insights into the future potential of the market, in addition to its current state. Firms should analyze a combination of elements like market size, competitiveness, and legal and political environments, understanding that choices involving international expansion have substantial and lasting implications.