Market Imperfections - Monopolies

Monopolies: Discuss the following statements in Detail
a) are a good thing since they transfer resources from lower-valued to higher- valued activities  thereby helping to maximize society’s happiness?
b) are bad because they produce too little output; thereby decreasing society’s happiness
c) a monopoly problem arises whenever Marginal Revenue (the change in Total revenue caused by an increase in output of one unit), is substantially less than Price at the firm’s profit-maximizing level of output
d) Can government regulation fix (a), (b), and (c) above ? if so how, if not why?