Option D – CH3CH≡CHCH3
An alkene is produced when dehydration of alcohol is performed. Alcohol dehydration is an example of an elimination reaction which is quite the opposite of substitution reaction and addition reaction.
The products of the dehydration of a primary alkanol are water and an alk-1-ene (1-alkene).
Butanol gives a mixture of but-1-ene and but-2-ene when dehydrated.