Problem: three interviewers , x , y , and z are interviewing 40 applicants . only with three interviewers ' admission can an applicant be admitted . if interviewer x admitted 15 applicants , y admitted 17 applicants , and z admitted 20 applicants , at least how many applicants get the admission ? 
Options: ['a ) 0', 'b ) 2', 'c ) 6', 'd ) 8', 'e ) 12']
a