What is the IUPAC name of the compound below?

CH3,CHCH2CH3
|
CH3,CCH2CH3
|
CH2CH2CH3

Select the correct response:
A) 2-sec-butyl-2-propylbutane
B) 4-ethyl-3,4-dimethylheptane
D) 3,4-dimethyl-3-propylhexane
E) none of these​