The correct answer is option 3 - Rajagriha. The first Buddhist Council was held in Rajagriha, which was the ancient capital of the Magadha kingdom in present-day Bihar, India. This council took place shortly after the death of Gautama Buddha around 483 BCE. The purpose of the council was to preserve the teachings and principles of Buddhism, as well as to reach a consensus on the Vinaya (code of conduct) for the Buddhist monastic order. It was attended by 500 arhats (enlightened disciples) led by Mahakassapa, who had been appointed by Buddha to maintain the sacred scriptures. The council lasted for several months and resulted in the compilation of the Tripitaka, the three baskets of Buddhist scriptures.