Identify the correct statement with reference to the extractive metallurgy of aluminium.

The electrolyte consists of molten Na$3$AlF$6$ with approximately $1$ to $8\%$ Al$2$O$3$

Approximately $80\%$ of the aluminium deposited on the cathode comes from cryolite

Sodium is deposited along with aluminium, but is immediately vaporised

Anode effect sets in when the cryolite concentration goes below $40\%.$