The chemical reaction in which alcohols and acids react with each other to form products as esters is called esterification.

Here, the organic acid group reacts with alcohol to form stable ester and water.

The mechanism of this reaction is nucleophilic acyl substitution.During this reaction the cleavage O-H bond of alcohols takes place.The reactivity for this cleavage goes down from primary to tertiary alcohol as the bulkiness of the substitutes on alcohol increases.
The alcohol acts as nucleophile here and also the steric effects support the reactivity order. Thus, tertiary alcohol is the least reactive than primary and secondary.

So, with acetic acid ethanol reacts the fastest followed by propanol and then 2-methyl propan-ol while the least reactive would be 2-3-dimethyl butan-1-ol.

Hence, the correct order of reactivity would be