The IUPAC name of the following compound is:

$\displaystyle 4$-methyl-$\displaystyle 3$-ethylhex-$\displaystyle 4$-ene

$\displaystyle 3$-ethyl-$\displaystyle 4$-methylhex-$\displaystyle 4$-ene

$\displaystyle 4$-ethyl-$\displaystyle 3$-methylhex-$\displaystyle 2$-ene

$\displaystyle 4$, $\displaystyle 4$-diethyl-$\displaystyle 3$-methylbut-$\displaystyle 2$-ene