Detailed Solution:
The correct answer is “Both A and R are true but R is not the correct explanation of A”.
Kushinagar, also known as Kusinara, was an important city in ancient India and was part of the Malla Republic. Kushinagar is famous as the place where Gautama Buddha attained Mahaparinirvana, which means he passed away there.
However, the reason (R) does not directly explain why Kushinagar was the capital of the Malla Republic.