It Is Spring,and Several Graduates of State U Are Seeking

It is spring,and several graduates of State U are seeking employment.State U graduates have evenly distributed GPAs,from 2.0 to 4.0,with an average GPA of 3.0.The largest employer in town,Acme Dynamite,is interviewing candidates,hoping to hire a few hard workers.While Acme does not require students to submit a transcript with their applications,the hiring officer believes that high GPAs signal a willingness to work hard.
Suppose that all State U students take the same courses and have the same academic abilities on entering college.They differ only by their tolerance for intensive study.If this is the case,a high GPA

A) does not provide useful information to Acme,since all applicants are of equal ability.
B) does not provide useful information to Acme,since all applicants took the same classes.
C) identifies students who don't mind studying,so is not costly information to convey and therefore not credible.
D) is a costly-to-fake indication that the high-GPA student is a hard worker.