Extent of dehydration by concentrated sulphuric acid I know that conc $\ce{H2SO4}$ is a dehydrating agent. And the most easiest mechanism for example would be this:

But I want to know how to find the extent of dehydration of it.
I came across this question:

And the answer is:

 d

My thinking:
(a) $\ce{O}$ is EN and will pull $\ce{-OH}$ towards itself inductively, thus decreasing the electron density on $\ce{-OH}$, and decreasing its power to pull $\ce{H}$ from concentrated $\ce{H2SO4}$.
Similarly for (b) and (c) and I think due to inductivity (c) will have more chances than (b).
As for the (d) I think $\ce{-CH3}$ group is an electron pusher so it should increase the electron density, and hence reducing the effect on $\ce{-OH}$ group .
1) But my doubt is: is this the only reason for the extent of dehydration by conc $\ce{H2SO4}$ on (d) to be more than (c)?
2) I don't think there would be much difference if it tautomerises to enol form.
The most stable Alkene is the most highly substituted Alkene. (d) gives a tri-substituted alkene, all others give the less disubstituted alkenes. Most stable Alkene (d) therefore more of it is formed! (Edited thanks to Bon for highlighting my error)

Also a factor to keep in mind is conjugation. (a), (b) and (d) will have conjugated double-bonds, while (c) will not. This conjugation also adds stability to the system. But the major stability contributor is the higher substituted alkene in (d).