For the reaction $A(g)+B(g) \rightleftharpoons C(g)$ at equilibrium, the partial pressure of the species are $P_{A}=0.15$ atm, $P_{C}=P_{B}=0.30$ atm. If the capacity of reaction vessel is reduced, the equilibrium is re-established. In the new situation, partial pressure $A$ and $B$ become twice. What is the partial pressure of $C$ :
(A) $0.3 atm$
(B) $0.6 atm$
(C) $1.2 atm$
(D) $1.8 atm$