The correct answer is:
D. as a record keeping system to keep track of economic information.
Explanation:
Quipus, also known as khipus or talking knots, were registering devices historically used in a number of cultures and particularly in the region of Andean South America. The cords included numeric and other values encoded by knots in a base ten positional system. The only potential Incan example of encoding and recording information could have been cryptic knotted strings identified as khipu.