The correct answer is $\boxed{\text{B}}$, $\ce{C6H6}$, benzene.
Aprotic solvents are solvents that do not contain a hydrogen atom bonded to an electronegative atom, such as oxygen or nitrogen. This means that they do not have a hydrogen bond donor, and they are therefore not able to participate in hydrogen bonding interactions with other molecules.
Water, $\ce{H2O}$, is a protic solvent because it contains a hydrogen atom bonded to an electronegative oxygen atom. This hydrogen atom can participate in hydrogen bonding interactions with other molecules, such as alcohols and acids.
Hydrogen fluoride, $\ce{HF}$, is also a protic solvent because it contains a hydrogen atom bonded to an electronegative fluorine atom. This hydrogen atom can participate in hydrogen bonding interactions with other molecules, such as alcohols and acids.
Ammonia, $\ce{NH3}$, is a protic solvent because it contains a hydrogen atom bonded to an electronegative nitrogen atom. This hydrogen atom can participate in hydrogen bonding interactions with other molecules, such as alcohols and acids.
Benzene, $\ce{C6H6}$, is an aprotic solvent because it does not contain a hydrogen atom bonded to an electronegative atom. This means that it does not have a hydrogen bond donor, and it is therefore not able to participate in hydrogen bonding interactions with other molecules.