The IUPAC name of is :

Based on the IUPAC nomenclature rules for organic compounds, here is the step-by-step breakdown to determine the correct name for the given structure:Identify the principal functional group: The molecule contains an acyl chloride group ($-COCl$). This gets the highest priority for numbering, so the carbon atom in the carbonyl ($C=O$) group is designated as carbon-1 (C1). The suffix for this functional group is -oyl chloride.Determine the longest carbon chain: Starting from the carbonyl carbon (C1) and tracing the longest continuous carbon path, we count 5 carbons. A 5-carbon chain corresponds to the parent alkane pentane. Combining this with our suffix gives us the base name pentanoyl chloride.Identify and locate substituents:At carbon-2 (C2), there is a line pointing upwards, representing a methyl group ($-C{H}_3$).At carbon-3 (C3), there is a line pointing downwards, representing another methyl group ($-C{H}_3$).Assemble the final name: Since there are two methyl groups, we use the prefix "di-" and state their positions on the chain. This gives us 2,3-dimethyl.Putting it all together, the full IUPAC name is 2,3-dimethylpentanoyl chloride.This corresponds to option 4.