Which of the following is weakest acid?

Greater the ‘+I’ groups(electron releasing groups) lesser the O – H polarity. This decrease the acidic nature.

The order of acidic strength of given compounds is

$\underset{\mathrm{Phenol}}{{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{OH}} >{\mathrm{CH}}_3\mathrm{OH} >\underset{\mathrm{Isopropyl} \mathrm{alcohol}\left(2^0\right)}{ \mathrm{CH}{\left({\mathrm{CH}}_3\right)}_2-\mathrm{OH}} > \underset{\mathrm{Tert}-\mathrm{butylalcohol}}{\mathrm{C}{\left({\mathrm{CH}}_3\right)}_3-\mathrm{OH}}$