Q. Which of the following language was lingua franca of India before Gupta era?
Answer: Prakrit
Notes: All the ancient civilizations of the world, including the Harappan Civilisation, had some common features like urban centers, surplus food production, development of art and craft, long distance trade and knowledge of writing etc.  Prakrit was the lingua franca of the country before it was replaced by the Sanskrit upto the Gupta Period. E.g. all the Ashokan inscriptions in the mainland India are written in the Prakrit language whereas, Rudradaman's inscription in post-Mauryan period was the first instance of usage of Sanskrit in an inscription.