When any person subject to this Act has been convicted by a court- martial of any offence, the Central Government, 1[the Chief of the Air Staff], an air or other officer commanding a group or the prescribed officer, may—
(a)either with or without conditions which the person sentenced accepts, pardon the person or remit the whole or any part of the punishment awarded; or
(b)mitigate the punishment awarded; or
(c)commute such punishment for any less punishment or punishments mentioned in this Act:
Provided that a sentence of transportation shall not be commuted for a sentence of imprisonment for a term exceeding the term of transportation awarded by the court; and a sentence of imprisonment shall not be commuted for a sentence of detention for a term exceeding the term of imprisonment so awarded;
(d) either with or without conditions which the person sentenced accepts, release the person on parole.