Question

Which of the following people is a member of the proletariat?

A. A university professor
B. A middle-class doctor
C. A mine owner
D. A factory worker

Answer 1

D. A factory worker

Answer 2

For the answer to the question above, it is letter D. Factory workers, because proletariat is a term for the class of wage-earners, in a capitalist society, whose only possession of significant material value is their labor-power (their ability to work).
I hope my answer helped you.