The dialogue on Varna between king Avantiputta and Kachchana, a discip

The dialogue on Varna between king Avantiputta and Kachchana, a disciple of Buddha, appears in which one of the following Buddhist texts?

Majjhima Nikaya
Samyutta Nikaya
Anguttara Nikaya
Ambattha Sutta
This question was previously asked in
UPSC CDS-2 – 2018
The dialogue concerning Varna between king Avantiputta of Mathura and the Buddhist monk Maha Kachchana appears in the Madhura Sutta, which is part of the Majjhima Nikaya of the Pali Buddhist canon.
The Madhura Sutta records a discussion where Maha Kachchana argues against the inherent superiority of the Brahmin varna and asserts that varna distinctions are not based on birth but on actions and moral conduct, using empirical examples to challenge the claims of purity associated with Brahmins.
The Majjhima Nikaya is the collection of ‘Middle-length Discourses’ and is one of the five main divisions (Nikayas) of the Sutta Pitaka, which is part of the Tipitaka, the sacred scripture of Theravada Buddhism.