Answer
Bases, in order of increasing Kb value, are:
$(c), (a)$ $and$ $(b).$
Work Step by Step
Higher Kb (with equal concentrations), means a higher number of $OH^-$, because the base will dissociate in a larger scale.
- (a) has 2 $OH^-$
- (b) has 3 $OH^-$
- (c) has 1 $OH^-$
Therefore, (c) has the lowest Kb value, (a) has the medium and (b) has the highest.