Which Is Not an Advantage of Using a Solid Electrolyte

Which is not an advantage of using a solid electrolyte in a fuel cell?

A) It is impermeable to liquids and gases and will keep the fuel and oxidizer separated.
B) It cannot "dry out" and will allow the fuel cell to operate at higher temperatures than one that uses water as part of the proton transfer mechanism.
C) It may use various fuels other than hydrogen gas,the fuel of choice in systems using water as part of the proton transfer mechanism.
D) It eliminates the need for an oxidant;only a fuel is requireD.