A Firm Hires Two Kinds of Workers, Alphas and Betas

A firm hires two kinds of workers, alphas and betas. The population at large has equal number of alphas and betas. One can't tell a beta from an alpha by looking at her, but an alpha will produce $3,000 worth of output per month and a beta will produce $2,500 worth of output in a month. The firm decides to distinguish alphas from betas by having workers take an examination. A worker will be paid $3,000 if she gets at least 60 answers right and $2,500 otherwise. For each question that they get right on the exam, alphas have to spend hour studying and betas have to spend 1 hour. For either type, an hour's studying is as bad as giving up $20 of income per month. This scheme leads to

A) a separating equilibrium where alphas score 60 and betas score 0.
B) a pooling equilibrium where alphas score 60 and betas score 0.
C) a pooling equilibrium where everybody scores 60.
D) a pooling equilibrium where everybody scores 0.
E) a separating equilibrium where everybody scores 60.