Hello Suraj

For B.A course in Delhi University,candidate can either apply through Merit Basis or through entrance exam for B.A hons.

In merit basis,12th marks would be considered and the cut off through Merit Basis is very high,but as you have mentioned that you belong to OBC,but still you need at least 94+% in 12th to get admission in best colleges of Delhi University through merit basis.

Now,talking about the entrance exam,you have to appear for DU JAT exam for UG courses such as BA hons,BBA and BMS. To get more information about this exam,you can check it out here

https://bschool.careers360.com/exams/du-jat

I Hope This Helps

Best Of Luck!!!