Detailed Solution:
The correct answer is “Both (A) and (R) are true and (R) is the correct explanation of (A)”.
The Himalayan region is one of the most seismically active regions in the world, and this is primarily due to the presence of numerous longitudinal thrust zones.
These thrust zones are created by the ongoing collision between the Indian and Eurasian tectonic plates, which are pushing against each other and causing the Himalayas to rise.