The correct answer is (b), Himalayan Frontal Thrust.
The Himalayan Frontal Thrust is a major thrust fault in the Himalayas. It separates the Lesser Himalaya from the Shiwalik Range. The fault is a result of the collision of the Indian and Eurasian plates. The Indian plate is moving northward at a rate of about 5 centimeters per year. This collision is causing the Himalayas to rise.
The Himalayan Frontal Thrust is a very active fault. There have been many earthquakes along the fault in the past. The most recent major earthquake was the 2015 Nepal earthquake, which had a magnitude of 7.8. The earthquake caused widespread damage in Nepal and India.
The Himalayan Frontal Thrust is a major geological feature that has had a significant impact on the landscape of the Himalayas. It is a fascinating and important fault to study.
The other options are incorrect.
(a) The Main Central Thrust is a major thrust fault in the Himalayas. It separates the Greater Himalaya from the Lesser Himalaya.
(c) The Main Boundary Fault (Thrust) is a major thrust fault in the Himalayas. It separates the Lesser Himalaya from the Sub-Himalaya.
(d) The Tethyan (Tethes) Fault is a major fault in the Himalayas. It separates the Himalayas from the Tibetan Plateau.