D) The presence of additional Br- ions already in the solution means equilibrium will be reached when much less CuBr has dissolved.
Explanation:
CuBr ⇄ +
Because there is Br- in CuBr, when put into solution, those Br- ions become part of the products side of the equation, shifting the equilibrium back towards the CuBr side, meaning less CuBr will dissolve.