Human rights activists have urged consumers to be conscious of the labor practices employed by manufacturers, especially in developing nations, saying that if we accept moral responsibility for our impact on third world workers, we must buy products from manufacturers that do not take advantage of their workers. It is nearly impossible, however, to determine which manufacturers are employing fair labor practices. Because of this impossibility there can be no moral obligation to choose products in the way these activists urge, because__. Which one of the following principles provides the most appropriate completion for the argument? ['A moral choice is more important than a moral action.', "The morally correct option is the one that maximizes a person's effort to do good.", 'It is more important to identify the moral choice than to act.', 'A person cannot have a moral duty to do what is impossible.']