Dear Student,

3B category comes under OBC in karnataka state. As per central some of the classes in 3B are OBC.

There is no rule regarding the category. If you belong to the 3B category this doesn't mean that you belong to the OBC category. As per the Central Government cast category, you must go and check you caste under the Government Policy.

There are some caste in 3B which are categorized under General category as per the Central Government.

You can visit website http://ncbc.nic.in for finding of your caste if it is in national list or not.

Hope this will help you.

All the best