B. As per decision of Federal Government
C. Speaker of National Assembly
D. Through polling in Parliament
49 Chairman or Speaker to act as, or perform functions of, President.
(1) If the office of President becomes vacant by reason of death, resignation or removal of the President the Chairman or, if he is unable to perform the functions of the office of President, the Speaker of the National Assembly shall act as President until a President is elected in accordance with clause (3) of Article 41.