Answer:
1st question: A
2nd question: D
3rd question: not so sure.... but I think B
4th question: not a or c.... I think B
Explanation:
Hey there,
Your question states: <span>How did the calculation of pi help mathematicians during the Gupta period?
My best guess that I would give would be the option B. </span><span>
The value of pi helped them explain that Earth is a rotating sphere. Because they used the </span>

to help them, just as we use that in math.
Hope this helps.
~Jurgen
The answer would be China as they have the most economic trade