Determinre the value of equilibrium constant `(K_(C))` for the reaction
`A_(2)(g)+B_(2)(g)hArr2AB(g)`
if 10 moles of `A_(2)` ,15 moles of`B_(2)` and 5 moles of AB are placed in a 2 litre vessel and allowed to come to equilibrium . The final concentration of AB is 7.5 M:
A. `4.5`
B. `1.5`
C. `0.6`
D. none of these