The correct answer is: a) Fault lines.
Hot springs are formed when water seeps into the Earth’s crust and is heated by magma or hot rocks. The heated water then rises to the surface through cracks or faults in the Earth’s crust.
Assam is located in a region of the world that is geologically active, with many fault lines. These fault lines provide a pathway for the heated water to reach the surface, creating hot springs.
Glacial deposits, volcanic craters, and limestone caves are not geological features that are associated with the formation of hot springs.
Glacial deposits are formed when glaciers melt and deposit their sediment. Volcanic craters are formed when volcanoes erupt. Limestone caves are formed when limestone is dissolved by water.