The original meaning of the word 'Vihar' is -

Correct answer: (a) Buddhist monastery

Explanation

The residence of Buddhist monks is called a Vihar (monastery). In ancient Sanskrit, Prakrit and Pali literature, there is no mention of any region named Bihar. Toward the end of the 12th century, due to the large number of Buddhist viharas in this region (especially around Odantapuri), it came to be called Vihar, which later became Bihar.