Solubility Product Expression, Ksp

What is the solubility product expression for mercury(I) chloride, Hg2Cl2?
A. Ksp= [Hg22+][2Cl-]2
B. Ksp= [Hg22+][Cl-]2
C. Ksp=[Hg22+][2Cl-]
D. Ksp= [Hg2][Cl2]
E. Ksp= [Hg+]2[Cl-]2