The equilibrium constant for the reaction `CaSO_(4).5H_(2)H_(2)O(s)hArr CaSO_(4).3H_(2)O(s)+2H_(2)O(g)` is equal to
A. `([CaSO_(4).3H_(2)O][H_(2)O]^(2))/([CaSO_(4).5H_(2)O])`
B. `([CaSO_(4).3H_(2)O])/([CaSO_(4).5H_(2)O])`
C. `[H_(2)O]^(2)`
D. `[H_(2)O].`