Explanation:

• The Penganga River originates from the Buldhana range of Maharashtra. It joins Wardha and the combined stream of them and Wainganga meets the Pranahita river. Pranhita finally joins the Godavari river.Thus, Penganga is a tributary of Godavari. Hence pair 1 is correctly matched.
• The Mahanadi is one of the major east-flowing peninsular rivers in India, originating in the Dhamtari district of Chhattisgarh and draining into the Bay of Bengal. The Seonath is the longest tributary of Mahanadi which rises in the midst of numerous small groups of hills in Rajnandgaon district of Chhattisgarh. Hence pair 2 is correctly matched.
• Barakar River originates from a place called Padma situated in the district of Hazaribagh in the state of Jharkhand. Barakar River runs down from west to east direction diagonally to the northernmost part of the Chota Nagpur table pours across 225 kilometers of the area and later merges into Damodar situated near Dishergarh of the district of Bardhaman in West Bengal. Hence pair 3 is correctly matched.
• A major tributary of the Cauvery River is the Bhavani River.The river is two hundred and seventeen kilometers long and flows through the states of Kerala and Tamil Nadu. Hence pair 4 is correctly matched.