Correct Option: A

The Third Buddhist council was convened in about 250 BCE at Asokarama in Pataliputra, supposedly under the patronage of Emperor Asoka. The traditional reason for convening the Third Buddhist Council is reported to have been to rid the Sangha of corruption and bogus monks who held heretical views. It was presided over by the Elder Moggaliputta Tissa and one thousand monks participated in the Council.