In an aqueous solution of volume 500mL, when the reaction of 2Ag⁺+Cu⇌Cu²⁺+2Ag reached equilibrium the [Cu²⁺] was xM. When 500mL of water is further added, at the equilibrium [Cu²⁺] will be :

A. 2xM
B. xM
C. between xM and x/2M
D. less than x/2M