Predict the product in the following reaction.

(A) $C{{H}_{3}}CHO$
(B)

(C)

(D)

Hint: The answer to this question is based on the concept of basic organic named reaction that is Wittig reaction where the reaction product formed in this reaction is the alkene and this fact gives you the required answer.

Complete answer:
We have come across the named reactions in our organic chemistry classes and also have known about which type of reaction the organic molecules undergo, that is there are several reactions like oxidation, reduction, substitution and also additional reactions.
Now, let us see the details of the Wittig reaction and the reagents used in the reactions which can help us to deduce the correct answer.
- Wittig reaction is a chemical reaction in which an aldehyde or ketone reacts with triphenyl phosphonium ylide which is also called as Wittig reagent to give an alkene and triphenylphosphine oxide.
The reaction of butyllithium and triphenylphosphine gives the ylide but since methyl iodide is used here, the reaction is as shown below,

This salt that is methyl triphenyl phosphonium salt and this salt further reacts with cyclopentanone to give the alkene,

Therefore, we get the product as aliphatic alkene with triphenyl phosphonium oxide that is $P{{h}_{3}}P=O$

Therefore, the correct answer is option C).

Note: Note that the Wittig reaction is also called as Wittig olefination reaction because it is an important method for the formation of alkenes that is the formation of double bonds at the place of aldehydes or ketones which were present originally in a molecule.