Keto-enol tautomerism does not observe in :
A. `C_(6)H_(6)-overset(O)overset(||)C-H`
B. `C_(6)H_(6)-overset(O)overset(||)C-CH_(3)`
C. `C_(6)H_(6)-overset(O)overset(||)C-CH(CH_(3))_(2)`
D. `C_(6)H_(6)-overset(O)overset(||)C-CH_(2)-overset(O)overset(||)C-CH_(3)`