Income tax -joint account-fixed deposit

Hello

I would like to know the tax payable for the interest from FC in bank for the following situation

There are two persons A (senior citizen) and B (not senior citizen and earningi person).  How the tax is calculated for person B ?

For example , if the joint account holders receives 1.25 lakh as interest from FD, how the tax is calculated for person B who is employed (not senior citizen) and for person B (senior citizen)?

Thanks