According to the A3 table Anna posted, Biology is not capped. It had a maximum scaled mark of 50/50. I think Anna said that Business Studies is capped at 91, but according to the table it had a max. scaled mark of 48.7/50, i.e. 97.4/100. To the OP: Economics wasn't capped and PE was capped at 48.8/50, i.e. 97.6/100 ... I think that means it might scale better the Business.
Choose to drop the subject you enjoy least, or if you enjoy Business and Economics equally, choose the subject in which you think you will get the worst mark.
P.S: I was interested to see that English Standard was capped at 47.9/50 ... I thought it scaled the same as Advanced ... maybe it does for all the marks lower than its capped mark.