What is the rate law for the following reaction and its mechanism?

1. What is the rate law for the following reaction and its mechanism? 

2 HgCl2 + C2 O4 2- → 2 Cl- + 2 CO2 + Hg2 Cl2 (overall reaction) 

HgCl2 + C2 O4 2- ⇌ HgCl2 C2 O4 2- (fast) 

HgCl2 C2 O4 2- + C2 O4 2- → Hg + 2 C2 O4 Cl2-(slow) 

Hg + HgCl2 → Hg2 Cl2 (fast) 

2 C2 O4 Cl2- → C2 O4 2- + 2Cl- + 2 CO2 (fast) 

A.Rate = k[HgCl2][C2O42-]2

B.Rate = k[Hg2Cl2] 

C.Rate = k[HgCl2]2[C2O42-]2 

D.Rate = k[HgCl2][C2O42-] 

E.Rate = k[HgCl2]2[C2O42-]