Hey!

As you want to take admission in B.A. programme after pursuing science in class 12th, you will have to face deduction in percentage. According to guidelines mentioned in bulletin of information released by University of Delhi, the inclusion of any subject other than those in List A and List B in the combination of best three will lead to a deduction of 2.5% per subject in the aggregate of the Best Four subjects.
You can go through the guidelines for each subject and undergraduate degree in the following link:
https://www.google.co.in/url?sa=t&source=web&rct=j&url=http://www.du.ac.in/adm2019/pdf/BulletinForUpload30May2019.pdf&ved=2ahUKEwjujIyYjpnjAhXP6nMBHZeVCV0QFjAAegQIARAB&usg=AOvVaw1mVQDQfLIPoIArqUZEZD2Z

You can view the Lists A and B in the link itself.

Hope it helps!