The correct answer is: Bhaga and Chandra Rivers.
The Bhaga and Chandra rivers are two of the most important tributaries of the Ravi River in Himachal Pradesh. The Bhaga River originates in the Pir Panjal Range and flows through the Kullu Valley before joining the Chandra River near the town of Mandi. The Chandra River originates in the Zanskar Range and flows through the Lahaul and Spiti Valley before joining the Bhaga River. The combined flow of the Bhaga and Chandra rivers then flows into the Ravi River.
The Bhaga and Chandra rivers are both important sources of water for irrigation and drinking water in Himachal Pradesh. They are also popular tourist destinations, with many people coming to the region to enjoy the beautiful scenery and to go white-water rafting and kayaking.
The other options are incorrect because they are not tributaries of the Ravi River. The Budhil and Siul rivers are tributaries of the Chenab River, the Tirthan and Sainj rivers are tributaries of the Beas River, and the Pabbar and Giri rivers are tributaries of the Sutlej River.