(N/A) $o-$Ethylanisole: $A$ benzene ring with a methoxy group $(-OCH_3)$ at position $1$ and an ethyl group $(-C_2H_5)$ at position $2$.
$(b)$ $p-$Nitroaniline: $A$ benzene ring with an amino group $(-NH_2)$ at position $1$ and a nitro group $(-NO_2)$ at position $4$.
$(c)$ $2,3-$Dibromo$-1-$phenylpentane: $A$ pentane chain with a phenyl group $(-C_6H_5)$ at position $1$ and bromine atoms at positions $2$ and $3$. The structure is $C_6H_5-CH_2-CH(Br)-CH(Br)-CH_2-CH_3$.
$(d)$ $4-$Ethyl$-1-$fluoro$-2-$nitrobenzene: $A$ benzene ring with a fluorine atom at position $1$,a nitro group at position $2$,and an ethyl group at position $4$.