Correct Answer: (a) Bihar and Uttar Pradesh
Note: 'Gandak Project' is a joint venture of India and Nepal as per the agreement signed between the two Governments on Dec. 4, 1959. Bihar and Uttar Pradesh are the participating Indian states. As a part of this bilateral agreement, the Gandak Barrage, a part of Gandak Project, was built in 1968-69 over the Gandak river for providing irrigation to Nepal, U.P. and Bihar. Nepal also gets electricity from this project,