The correct answer is B. They were one of two civilization to independently devise the concept of zero.
The three mathematical system which were constituted by Maya were
1. Dot which represented value of one.
2. Bar which represented five.
3. Shell which represented zero.
The symbols were used to track events in a calendar. For their calculations they used vigesimal system. For example, 1, 20, 400, 8,000.
Some of their numbers were calendar dates and were being written from the bottom side to the top side.
