The correct answer is

D

So here the correct answer is "D"

These three types of isomerism are shown in Pentanone

• Chain Isomerism
• Position Isomerism
• Functional Isomerism

Let's discuss how?

First, we should know about what is Isomerism?

Isomerism - Isomerism is the phenomenon in which more than one compounds have the same chemical formula but different chemical structures.

We have given compound pentaone , Below we are making the structure of 5 Carbon chain for pentaone compound

Structure of compound shown below after adding ketonic functional group and balancing

Now we will check for which isomerism is possible here

Chain isomerism - First, Here 5 carbon chain possible also a compound available that have 4 & 3 carbon chain and have the same molecular formula, Than structure will be - 

Now we will calculate the molecular formula of both figure Isomerism & Chain Isomerism

As shown above, both have the same Molecular formula than Chain Isomerism is possible here.

Position Isomerism - Position isomerism, an example of structural isomerism, occurs when a functional group is in different positions on the same carbon chain.

As shown above, We got the same molecular formula of functional group, So Position isomerism is possible of Pentanone

Functional Isomerism - Functional isomerism occurs when substances have the same molecular formula but different functional groups.

As shown in the above image all formulas have Ketonic group, If we replace the Ketonic group with an Aldehydic group, then the molecular formula will be the same again. So Functional Isomerism is possible in Pentaone