Please solve

Q.  The correct IUPAC name of the compound

(A) 5, 6-Diethyl-8-methyldec-6-ene
(B) 6-Butyl-5-ethyl-3-methyloct-4-ene
(C) 5,6-Diethyl-3-methyl-4-ene
(D) 2,4-5-Triethylnon-3-ene

Dear Student,

In naming the compound according IUPAC, firstly the longest chain containing the functional group is identified. 

Hence in the given structure, the longest chain is 10 carbon .
And the nearest substituent is at 3rd position so, according to it the the IUPAC name will 5,6-diethyl-3-methyl-dec-4-ene .

But this is not in the option so, next the chain of 8 carbon is selected and nearest methyl substituent will be at 3rd position. 
Hence the IUPAC nomenclature according to it will be : 
                                    6-butyl-5ethyl-3-methyl-oct-4-ene

So, the correct option is (B).

Regards.