Buddha delivered his first sermon, known as the "Dhammacakkappavattana Sutta" (Setting in Motion the Wheel of Dharma), at Sarnath near Varanasi.
Step 1: Importance of Sarnath
This event marked the beginning of Buddha’s teaching and the foundation of Buddhism.
Step 2: Clarify other locations
- Bodh-Gaya is where Buddha attained enlightenment.
- Rajagriha and Kapilavastu are important locations in his life but not where the first sermon was given.
Thus, option (A) is correct.