please give us your comments on college applications

Son felt very sad because he was denied by one of the colleges he likes to go the most. We are wondering if it is because his grades are not good at math, but on the application we applied for engineering. His grades are very good at history, but we do not think it is a good major to study. what do you think ? should the major applied effect the admission ? for the college he got denied, there are choices for the majors on the first choice, second, and the third. So I think it is because son's ACT or GPA does not meet the requiremen. Please give me your comments. thank you in advance.