The answer is "b. because individual actions often have important consequences and costs for society".
Society is a noteworthy factor in what condition people get themselves conceived, raised, and living in. To that degree, society bears a more profound and more ethically responsible obligation than any person inside it in an indistinguishable sense from the misfunctioning PC's condition does. Actions of an individuals that are living in society are very important as they make the society good or bad.