The correct option is B Later Vedic age
The concept of 'Gotra' became established in Later Vedic age. The institution of gotra appeared in later Vedic times. Literally, it means the “cow-pen” or the place where cattle belonging to the whole clan are kept. The gotra has been regarded as a mechanism for widening the socio-political ties, as new relationships were forged between hitherto unrelated people.