In DU, courses that come under category of faculty of sciences and applied sciences consider your best of three. you have to check the bulletin of information to know which subjects to consider while calculating best of three. For example, for admission into bsc hons in microbiology, you take PCB combination.

Best wishes

hey prateek

for du admisssions it is necessary to calculate best for four marks . there are not any colleges which take admissions on the basis of best of three . if your marks becomes lesss for best of 4 than look out for other courses .you can also try b voc from DU

http://du.ac.in/du/uploads/03092016_BVoc.pdf

best wishes