The most accurate response regarding how Buddhism affected India is:
It offered an alternative to the rigid caste system of Hinduism.
Buddhism emphasized individual spiritual development and compassion, appealing to those who faced discrimination under the caste system, thus providing a different social framework. While Buddhism did gain significant followers and influence, it did not replace Hinduism as the major religion in India, nor did it change the culture to a monotheistic focus. It also did not lead to a political uprising that toppled the Indian government.