$12$ Which of the following statements about marketing environment forces is NOT true?

a$.$ They do not influence customers' reactions to a firm's marketing mix.

b$.$ They influence customers by affecting their lifestyles, standards of living, and preferences and needs for products.

C$.$ They fluctuate quickly and thereby create threats to a firm's marketing mix.

d$.$ They may create opportunities as well as threats.

e$.$ They influence whether and how a marketing manager performs certain marketing activities.