Marketing decision makers in a firm must constantly monitor competitors' activities - their products, prices, distribution, and promotional efforts - because:

a) the competitors may be violating the law and can be reported to the authorities.

b) the actions of competitors may threaten the monopoly position of the firm in its industry.

c) the actions of competitors may create an oligopoly within an industry.

d) new product offerings by a competitor with the resulting competitive variations may require adjustments to one or more components of the firm's marketing mix.