In test marketing, the greatest danger is in choosing a test$-$site city that $\_\_\_\_\_\_$

a$.$

does not respond quickly to changing trends and is highly entrenched in its cultural ways

b$.$

has a racial mix and thus has more diversity than other cities in the projected market area

c$.$

does not reflect market conditions in the new product$$s projected market area

d$.$

is unique in being representative of the entire city, although it is unlike neighboring cities