Balance the following reactions. Which of the reactions requires the least number of total moles to reactant?

FeCl2 (aq) + Na3PO4 (aq) --> Fe3(PO4)2 (aq) + NaCl (aq)
CaI2 (aq) + H2SO4 (aq) --> HI (aq) + CaSO4 (aq)
P2O5 (s) + H2O (l) --> H3PO4 (aq)
Al (s) + Cl2 (g) --> AlCl3 (s)
a) 1
b) 2
c) 3
d) 4