ANS:D - NOR gate

If we take 2ips A=0, B=0 starting bubble means invertion of given values that means A=1, B=1 for these AND operation we can perform it gives 1 is the op.

Like that we sub all 01,10,11 the ops of these are 0,0,0 finally we get 1,0,0,0 this is like NOR operation so This symbol is equal to NOR gate.