The correct answer is option 4, which indicates that all four individuals mentioned in the options were the Speakers of the Lok Sabha.

Option 1, M.A. Ayyangar, served as the Speaker of the Lok Sabha from 1956 to 1957.

Option 2, G.S. Dhillon, served as the Speaker of the Lok Sabha from 1962 to 1967.

Option 3, Balram Jakhar, served as the Speaker of the Lok Sabha from 1980 to 1989.

Option 4, P.A. Sangma, served as the Speaker of the Lok Sabha from 1996 to 1998.

All four individuals have held the prestigious position of the Speaker of the Lok Sabha at different points in time. It is important to note that the question specifically asks about the total number of individuals who have served as the Speaker of the Lok Sabha, and the correct answer is all four mentioned in the options.