Answer:
The correct answer is letter "C": there still would be an economic problem.
Explanation:
Coordination, in Economics, refers to the set of actions different individuals take to satisfy their needs mutually. Problems arise in case there is not enough coordination of the individuals in an economy bringing lower benefits for them. For coordination to take place there must be a leader driving people's activities the most efficient way possible.
In the case of the example, after taking a pill that made people selfless, those individuals would still lack coordination because it would be difficult to determine which sector of individuals will be the priority for the satisfaction of needs. Therefore, even after the introduction of the pill, that society would give an economic problem.