Hello,

Since you had asked the question in the year 2019, I hope you have completed your 12th boards till now and got admission in any of the decent college.  But,  If not yet,then let me tell you yes,  you can give improvement exam in all the subjects or either of your choice. But, if you are a CBSE student, then let me clear you that as per the latest update, your improvement examination marks will be considered as final marks.

Hope this answer will help you.

Thank you!

Good luck!