Rate of dehydration of alcohols having keto group The following question was asked in IITJEE-Screening 2000,

Which of the following will be most readily dehydrated in acidic conditions?


I thought that the answer would simply be (c), as its intermediate would be stabilized by resonance with keto group and it is a sec-carbocation (which is common in all the options, so deosn't matter).
But my answer was wrong as per answer key. Am I missing something?

The correct answer as per key was,

 (a)
A carbonyl group normally destabilizes carbocations but stabilizes carbanions.
In this particular case, the rate of dehydration isn't guarded by carbocation stability, but by CH- acidity. In acidic conditions, OH group in alcohols is relatively easily protonated. Then, if there is a relatively acidic hydrogen in $\beta$-position it immediately dissociates, together with a water molecule.
Excercise: Try to draw a mechanism for dehydration of (a) in basic conditions. Hint: it does occur and produces the same product. It does require more heating, though.