What is the precursor to pinacolone in the pinacol rearrangement?

A. 2,3-dimethylbutane-1,4-diol
B. 2,3-dimethylpropane-1,2-diol
C. 2,3-dimethylbutane-1,2-diol
D. 2,3-dimethylbutane-2,3-diol
Answer: 