The correct option is B 5,6-diethyl-3-methyl-4-decene
The parent hydrocarbon contains 10 carbon atoms and a double bond between fourth and fifth carbon atom.
Hence, it is named 4decene.
Also one methyl substituent is present at third carbon atom and two ethyl substituents are present at fifth and sixth carbon atoms.
Hence, IUPAC name of compound is 5,6Diethyl3methyl4decene.