The answer is # 4 they develped the concept of zero in the use of math and also created the decimal system based on the number 10 , the Arabic number system, a number writing system used all over the world today
I believe the answer is: (4)Development of the concept of zero
The concept was developed by the studies from various scholar, most notably a mathematician named Aryabhata and it become the basis that is used for modern mathematics that we see today. This concept would even play a more crucial role int the field of engineering because due to the use of 1 and 0 as binary numbers.
