Cooper owns and operates CoopersCuts, a lawn care company with $8$ year$-$round employees. Each summer, when demand for CoopersCuts' services increases, Cooper asks his employees to inform him of any of their friends and neighbors who might be interested in being hired. He encourages his staff to 'ask around' at cookouts, softball games, barbershops, and other places they interact socially. Cooper's efforts to recruit in this way:

a$.$ are specifically prohibited by the Civil Rights Act because of their potential to produce discriminatory effects

b$.$ are not optimal recruiting procedures, but raise no significant legal concerns

c$.$ may be legal but are inadvisable given the potential to produce discriminatory effects depending on how homogeneous an employer's existing workforce is

d$.$ are specifically prohibited by the Eliot Larsen Civil Rights Act if CoopersCuts is located in Michigan