The Chambal river merges with the Yamuna river, not with the other mentioned rivers.

Option 1: Banas river is not the correct answer because the Chambal river does not merge with the Banas river.

Option 2: Ganga (Ganges) river is not the correct answer because the Chambal river does not merge with the Ganga river.

Option 3: Narmada river is not the correct answer because the Chambal river does not merge with the Narmada river.

Option 4: Yamuna river is the correct answer because the Chambal river merges with the Yamuna river. The confluence of the two rivers is known as the Triveni Sangam, which is located at the border of Madhya Pradesh and Uttar Pradesh in India.

In conclusion, option 4 is the correct answer as the Chambal river merges with the Yamuna river.