Answer:
Correct answer is C. Ashoka the Great became a Buddhist.
Step-by-step explanation:
Option A is not correct as Hinduism is still the most practiced religion in India.
Option B is also not correct as caste system remained effective.
Option C is correct. Ashoka was the greatest ruler of Mauryan dynasty who embraced Buddhism.
Option D is not correct as Buddhism had its roots in India and later spread across the globe.