What is the equilibrium expression for the reaction $P_{4(s)} + 5O_{2(g)} \leftrightharpoons P_4O_{10 (s)}$?

Question

( A ) $Kc=[P_4O_{10}] / P_4] [O_2]^5$
( B ) $Kc=[P_4O_{10}]/5[P_4][O_2]$
( C ) $Kc =[O_2]^5$
( D ) $Kc =1/[O_2]^5$