This is destroyer question 7 in orgo.

The answer is D) 3-hydroxy-2-methlypentanal

However, shouldn't the -OH on one carbon and -H on the adjacent carbon leave in the form of water thus making a double which owuld mean the answer choice SHOULD be E) 2-methyl-2-pentEnal?

this is an aldol condensation and what you are saying is right under one condition. First it forms a molecule with an aldehyde and a hydroxy. Now if heat is added to that, you lose a water molecule forming a double bond. So unless you see heat as the next step, you stop at that answer.

naw because it wasn't a condensation. if there were heat added, it would be an aldol condensation. otherwise its just an aldol reaction.

Aah, I see. Thanks for the tip guys!

only when you add heat after then the H2O will leave

The only time where you do not need to add acid and heat to get the dehydration product is if you react something like methyl phenyl ketone with formaldehyde (in base). In this case, there is absolutely no need to add acid and heat because of the strong driving force to make the alpha-beta unsaturated ketone which would be in complete conjugation with the benzene ring. Also, if you reacted benzaldehyde with acetone, etc, you would not have to add acid and heat to get the full conjugated system because the driving force for full conjugation is so large. Otherwise, all the above posts are correct. Acid and heat will be needed to form the dehydrated product.

only when you add heat after then the H2O will leave