The correct option is A NO2
HNO3 is a strong oxidising agent. Concentrated HNO3 oxidises better than dilute HNO3. When Zn reacts with dil.HNO3, NO gas is evolved. On the other hand, NO2 is released, when Zn reacts with conc.HNO3.
3Zn+8HNO3(dil)→3Zn(NO3)2+4H2O+2NO↑
Zn+4HNO3(conc.)→Zn(NO3)2+2H2O+2NO2↑