Hello.

The criteria for clearing JEE mains and Advanced examination is that you have to get a minimum of 75% in your respective board. But since you've got only 71% in 12th, I don't think that you will get selected. Instead of taking a drop, I think you should write 12th exams once again. You can always apply for the improvement examination.

But if you don't want to write it once again, don't worry. There are many colleges which don't have that criteria. SRM University, Amity University, VIT Vellore, all these colleges conduct their own examinations. You can apply in them too.

All the best!!