Electrolysis of NaCl (aq) is carried out using inert electrodes, choose the correct option(s):

A. When concentrated NaCl is used, oxygen gas is liberated at anode.
B. When dilute NaCl is used, chlorine gas is liberated at anode.
C. When concentrated NaCl is used, chlorine gas is liberated at anode.
D. When dilute NaCl is used, oxygen gas is liberated at anode.