A niche marketer is considered to be a$($n$)\_\_\_\_\_\_\_\_$ specialist if the firm specializes in producing a certain type of product or product feature such as Rent$-$a$-$Wreck, which rents only "beat$-$up$"$ cars.

Group of answer choices

A$)$ end$-$user

B$)$ vertical$-$level

C$)$ customer$-$size

D$)$ channel

E$)$ product