the incas developed a record - keeping system using shells and beads on strings. knots and designs in…

Brief Explanations:

The Incas used a quipu, which was a system of knots and designs in strings to record information such as population, taxes, and historical events. Shells and beads on strings were not their record - keeping method. They did not have a fully developed writing system like some other civilizations (though they had some forms of visual communication that were not writing in the traditional sense), so writing and pictographs are incorrect. Numbers and calculations were part of what the quipu could represent, but the physical form was knots and designs in strings.

Answer:

knots and designs in strings.