108. A person shall be disqualified for being a voter
(a) if he is of unsound mind and stands so declared by a competent court;
(b) if he is serving a sentence of transportation or of imprisonment for a criminal offence involving moral turpitude;
(c) if he has been convicted of an offence, or found to have been guilty, of corrupt or illegal practice, relating to elections of a Legislature within five years of the election concerned.