Plz Help I didn't understand these

How did advancements during the Gupta period transform mathematics?

A. They invented algebra.

B. They created the concepts of square numbers and square roots.

C. They developed a decimal system with a numeral for zero.

D. They made progress in metallurgy.

Under whose reign did the Gupta empire reach its greatest size?

A. Chandragupta Maurya

B. Chandra Gupta I

C. Samudra Gupta

D. Chandra Gupta II

Which game was invented in India?

A. solitaire

B. mahjongg

C. chess

D. checkers