The image of the structure is attached in the image below.
Answer: The correct option is a.) 4-methyl-3-phenyl-3-pentenoic acid
Step-by-step explanation:
Carboxylic acids are a type of functional group in organic chemistry that have the symbol '-COOH'. A suffix used for this functional group is '-oic acid'.
To name a compound, first look for the longest possible carbon chain.
As in the image attached below, the longest carbon chain has 5 carbon atoms. Thus, the prefix used will be 'pent-'
Also, a methyl substituent is present at the 4th position, a phenyl substituent is located at the 3rd position.
A double bond is also present at the 3rd position and a suffix '-ene' is used.
Hence, the IUPAC name for the given compound is 4-methyl-3-phenyl-3-pentenoic acid.