The correct answer is: Prakrit.
Prakrit is a group of Middle Indo-Aryan languages that were spoken in India from the 6th century BCE to the 12th century CE. It is the ancestor of modern Hindi, Marathi, Gujarati, and other Indo-Aryan languages.
Prakrit was used in inscriptions, literature, and religious texts from the Mauryan Era (322-185 BCE) to the Gupta Era (320-550 CE). It was also the language of the common people, while Sanskrit was the language of the elite.
Pali is a Prakrit language that was used in the Buddhist scriptures. It is closely related to Magadhi Prakrit, which was the language spoken in the region of Magadha, where the Buddha lived.
Sanskrit is an Indo-Aryan language that was used in ancient India. It is the language of the Vedas, the oldest Hindu scriptures. Sanskrit was also the language of the elite in the Mauryan Era.
Magadhi Prakrit is a Prakrit language that was spoken in the region of Magadha, where the Buddha lived. It is closely related to Pali, the language of the Buddhist scriptures.
In conclusion, the major language used in inscriptions from the Mauryan Era was Prakrit.