Which Classification of Alcohols Cannot Be Oxidized, and Why

Multiple Choice

Which classification of alcohols cannot be oxidized, and why?

A) tertiary, because they don't have a hydrogen on the carbon adjacent to the alcohol
B) tertiary, because the alcohol is already attached to four atoms
C) secondary, because they are too hindered by carbons adjacent to the alcohol
D) primary, because they undergo competing reactions in the presence of an oxidant
E) primary, because the reaction takes too much energy