The correct answer for the question "The `Pong Dam` is constructed on the river" is option 3, Beas. The Pong Dam, also known as the Maharana Pratap Sagar, is a dam on the Beas River in the state of Himachal Pradesh, India. It is one of the highest earthfill dams in the country and is a popular tourist destination. The dam provides irrigation water to the states of Himachal Pradesh, Punjab, and Rajasthan, and also serves as a hydroelectric power station. The construction of the dam was completed in the year 1974, and it has since played a vital role in the agricultural and power sectors in the region.