The correct answer is: A. Yamuna River
The Yamuna River is a major river in India and is one of the most polluted rivers in the world. Lead is one of the most common pollutants found in the Yamuna River. Lead can be found in the river due to industrial pollution, mining activities, and the use of lead-based paint. Lead is a toxic metal that can cause a variety of health problems, including brain damage, kidney damage, and reproductive problems.
The Tons River is a tributary of the Yamuna River. The Tons River is also polluted, but it is not as polluted as the Yamuna River. Lead is found in the Tons River, but it is not found in as high concentrations as it is in the Yamuna River.
The Giri River is a tributary of the Tons River. The Giri River is not as polluted as the Tons River, and it is not as polluted as the Yamuna River. Lead is not found in the Giri River.
The Sutlej River is a tributary of the Indus River. The Sutlej River is not polluted with lead.
In conclusion, the Yamuna River is the river where lead metal is found at the bottom.