What is difference between additional and optional subject orIs there any problem who choose biology as 4th optional (pcmb) instead pcbm
Hii
Optional
Subject are those which you have taken as Optional and there marks will not be added in your 12th Result when you apply for admission.
In your case, you can apply for both JEE Mains & NEET Exam, were PCM score & PCB score will be validated respectively.
NEET Eligibility Criteria 2019
https://medicine.careers360.com/articles/neet-eligibility-criteria
JEE Mains Eligibility Criteria 2019
https://engineering.careers360.com/articles/jee-main-eligibility-criteria
All the best.