When a mixture consisting of 10 moles of `SO_2` and 16 moles of `O_2` were passed over a catalyst , 8 mole of `SO_3` were formed at equilibrium.The number of moles of `SO_2` and `O_2` which did not enter into reation were :
A. 2,12
B. 12,2
C. 3,10
D. 10,3