The correct answer is option 2, Ganga-Brahmaputra Valley. The Ganga-Brahmaputra Valley, located in the northern part of India, is known for its high seismic activity. This region is prone to earthquakes due to its location on the boundary between the Indian and Eurasian tectonic plates. The convergence of these plates leads to the formation of faults and the buildup of stress, resulting in frequent seismic activity. The earthquakes in this region can range from minor tremors to major earthquakes that cause significant damage. It is important to note that while other regions mentioned in the options may also experience earthquakes, the Ganga-Brahmaputra Valley is considered to be the most prone to seismic activity in India.