The correct answer is option 3, Rajasthan. Khetri is an area in Rajasthan that is known for its copper ores. Copper mining and extraction activities have been carried out in Khetri for many years, making it an important area for copper production in India. Copper ores are rocks or minerals that contain copper in high concentrations and can be extracted for various industrial uses. Khetri`s location in Rajasthan, known for its rich mineral resources, has made it an ideal place for copper mining. The area has witnessed significant copper production and has contributed to India`s overall copper production. It is important to note that the other options, Himachal Pradesh, Assam, and Karnataka, are not known for copper ores, so they are incorrect in this context.