Solubility Product Expression, Ksp

What is the solubility product expression for Pb3(PO4)4?
A. Ksp= [Pb3+]4[PO44-]3
B. Ksp= [3Pb3+][4PO43-]
C. Ksp= [3Pb3+]3[4PO43-]4
D. Ksp= [Pb2+]3[PO43-]2
E. Ksp= [Pb4+]3[PO43-]4