The correct IUPAC nomenclature for the following compound is:
\( 2 \)-Methyl-\( 5 \)-oxohexanoic acid
\( 5 \)-Methyl-\( 2 \)-oxohexan-\( 6 \)-oic acid
\( 2 \)-Formyl-\( 5 \)-methylhexan-\( 6 \)-oic acid
\( 5 \)-Formyl-\( 2 \)-methylhexanoic acid