The correct option is
C Hex-4-en-2-one![](https://search-static.byjusweb.com/question-images/byjus/infinitestudent-images/ckeditor_assets/pictures/20482/content_new_218666_s1.png)
The above compound has a double bond and a ketone as the functional group. The primary suffix while naming the molecule is “-ene”. The secondary suffix is “one”. It is given that the rightmost carbon is the first carbon in the main chain. It is because the functional group ketone has priority over alkene. Let's assign numbers to the carbons in the compound.
![](https://search-static.byjusweb.com/question-images/byjus/infinitestudent-images/ckeditor_assets/pictures/20483/content_new_218666_s2.png)
Now while writing the chemical name, we have to mention the position of the double bond and ketone in the name. The name of the compound is “Hex-4-en 2-one.”