The correct answer is option 3, K2. K2 is the second highest peak in the world, after Mount Everest. Although option 1, Dhaulagiri, is one of the highest peaks in the world, it is not the second highest. Similarly, option 2, Kanchenjunga, is the third highest peak in the world, not the second. Option 4, NandaDevi, is also not the second highest peak in the world. Therefore, the correct answer is option 3, K2, as it is the second highest peak globally. It is important to note that the heights of mountains can vary slightly based on different measurements, but K2 consistently ranks as the second highest peak.