Dear Pushkar, the Groups are based upon the no. of years the Insured card has been in the service with ESIC. It is not about age. Lets say your father has the ESIC Insurance card, if hemhas more than 5 years of experience either as in contract or in service, then you fall under Group A. It is 4 years for Group B and 3 years for Group C. And once the seats are filled in accordance to these groups, if there are seats left, the rest of the candidates are constituted and formed as Group D.