Which of the following statements is most correct?

a. The ability of firms to engage in socially beneficial projects that involve voluntary costs is constrained by competition.

b. The actions that maximize a firm's stock price are always inconsistent with maximizing social welfare.

c. The concepts of social responsibility and ethical responsibility on the part of corporations are completely different and neither is relevant in maximizing stock price.

d. If government did not mandate socially responsible corporate actions, such as those relating to product safety and fair hiring practices, firms in competitive markets would not pursue such policies voluntarily.