Final answer:
The quote "duty was his main forte" about Birbal Sahní is attributed to Prof. TS Sadasivan.
Step-by-step explanation:
The quote "duty was his main forte" about Birbal Sahní is attributed to Prof. TS Sadasivan and not any of the other options mentioned. This quote suggests that Birbal Sahní was known for being dutiful. However, it is important to note that Birbal Sahní is not a historical figure, and there may be limited information available about him outside of the context provided in the question.
Learn more about Birbal Sahní and the quote about his duty