<span>When a scientific experiment is carried out in a controlled setting, all variables are kept the same except for the _control______ variable control variable is something that is kept constant and is unchangeable so i conclude option C is correct hope it helps</span>
Reason - Frog is using water pools of water collect by flower. Which benefits the frog :) Then the frog also dispersed its waste which then also the flower can use for its benefits. So in all it's mutualism