Which statement expresses the American Marketing Association $($AMA$)$s core definition of marketing?

a$.$ Marketing refers to personal selling that focuses solely on selling goods, services, and$/$or ideas to customers.

b$.$ Marketing involves building long$-$term, mutually rewarding relationships that are beneficial exclusively to the sellers.

c$.$ Marketing is an organization function and a set of processes that have value for customers, clients, partners, and society at large.

d$.$ Marketing is a philosophy, an attitude, a perspective, or a management orientation that stresses employee satisfaction.