The correct answer is: a) Central Assam.
Assam is located in a seismically active region, and earthquakes are a common occurrence. The region most prone to earthquakes in Assam is Central Assam. This is due to the presence of the Shillong Plateau, which is a geologically unstable region. The Shillong Plateau is located on the boundary between the Indian and Eurasian tectonic plates, and this boundary is a major fault line. Earthquakes can occur when the plates move past each other, and this is what causes the earthquakes in Central Assam.
The other options are incorrect because they are not the regions most prone to earthquakes in Assam. Northern Assam is located on the Brahmaputra River, and this region is not as seismically active as Central Assam. Southern Assam is located on the Bay of Bengal, and this region is also not as seismically active as Central Assam. Western Assam is located on the Indo-Gangetic Plain, and this region is the least seismically active region in Assam.
In conclusion, the region most prone to earthquakes in Assam is Central Assam. This is due to the presence of the Shillong Plateau, which is a geologically unstable region. The Shillong Plateau is located on the boundary between the Indian and Eurasian tectonic plates, and this boundary is a major fault line. Earthquakes can occur when the plates move past each other, and this is what causes the earthquakes in Central Assam.