Students should have bonus option
Rather than just having bonus points for one subject, why not consider extending this concept using a system of weighting the points in various subjects?
Taking six or more subjects could still be obligatory in order to matriculate and encourage a broad set of skills and knowledge, but in addition to this each college course could name particular subjects they would accept as “weighted subjects” – even going so far as to decide the “weighting factor” they would place on particular subjects. Then candidates’ results could be optimised by using the weighting factor in those particular subjects to assist entry to their chosen courses.