During the extraction of aluminium using electrolysis, cryolite is introduced to the bauxite ore. Which row states the function of cryolite and shows the ionic half-equation at the cathode?
- Arole: catalyst; $\text{Al}^{3+} + 3e^- \rightarrow \text{Al}$
- Brole: catalyst; $\text{Al}^{3+} + 3e^- \rightarrow 3\text{Al}$
- Crole: lowers melting point of electrolyte; $\text{Al}^{3+} + 3e^- \rightarrow \text{Al}$
- Drole: lowers melting point of electrolyte; $\text{Al}^{3+} + 3e^- \rightarrow 3\text{Al}$