The correct answer is: c) 2011.
On 15 April 2011, a magnitude 6.9 earthquake struck Arunachal Pradesh, India. The epicenter was located near the town of Tawang, and the earthquake was felt in several other states in India, as well as in neighboring countries such as Bhutan, China, and Myanmar. The earthquake caused significant damage to buildings and infrastructure in Arunachal Pradesh, and there were several fatalities.
The earthquake was caused by the movement of the Indo-Australian Plate and the Eurasian Plate. These two plates are constantly moving, and the friction between them builds up over time. When the friction becomes too great, the plates suddenly slip, causing an earthquake.
The 2011 Arunachal Pradesh earthquake was a reminder of the seismic activity that is common in the region. It is important to be prepared for earthquakes, and to have a plan in place in case one occurs.
Option a) 1980 is incorrect. There was no major earthquake in Arunachal Pradesh in 1980.
Option b) 1950 is incorrect. There was a major earthquake in Assam in 1950, but it did not strike Arunachal Pradesh.
Option d) 2015 is incorrect. There was a major earthquake in Nepal in 2015, but it did not strike Arunachal Pradesh.