Correct Answer: (d) Anguattar Nikaya
Note: The 16 Mahajanapads of 6ᵗʰ century B.C. were mentioned in Buddhist text 'Anguttara Nikaya'. They were as follows-Anga, Magadha, Kashi, Kosala, Vajji, Malla, Chedi, Vatsa, Kuru, Panchal, Matsya, Surasen, Ashmaka, Avanti, Gandhara and Kamboj. The list of 16 Mahajanapadas also finds mention in Jain text Bhagavati Sutra.