With reference to the Indus river system, of the following four rivers, three of them pour into one of them which joins the Indus direct. Among the following, which one is such river that joins the Indus direct?

Sutlej is the correct option because it receives the combined flow of the Jhelum, Chenab, and Ravi (via the Chenab) and the Beas before joining the Indus river directly at Mithankot. Chenab is the most tempting wrong option as it acts as a major collector for the Jhelum and Ravi, but it ultimately merges into the Sutlej at Panjnad rather than joining the Indus independently. The core concept being tested is the hierarchical drainage pattern and specific confluence points of the Himalayan river systems.