The answer is B) New interpretations of Buddhism were introduced
Ashoka was the last emperor in History who contributed towards the growth and expansion of the Bhuddist religion in the Indian Sub continent.
After his death, things quickly went downhill for the religion. Many local monks started to internet the religion in their own way, contributing towards the distinct practices of Bhuddism found in the South of Indian and the Himalayas.
The eventual rise of the Gupta Empire and then the Mongol-Turk invasions brought Islam to the sub-continent leading to a drastic fall in Buddhists.