The rate expression for the reaction between iodine and propanone with an acid catalyst is found to be:

$${\text{rate}} = k{{\text{[}}{{\text{H}}^ + }{\text{]}}^1}{{\text{[}}{{\text{I}}_{\text{2}}}{\text{]}}^0}{{\text{[C}}{{\text{H}}_{\text{3}}}{\text{COC}}{{\text{H}}_{\text{3}}}{\text{]}}^1}$$

What is the overall order of the reaction?

A.     0

B.     1

C.     2

D.     3

C