Read the last paragraph of the article.

The Incas might have failed to develop a way to represent words with symbols. Or maybe we have been underestimating them. Perhaps they had their own very special way of telling stories. We might be closer to finding that out.

How does this paragraph support the main idea of the article?
A. It highlights the idea that khipu could have been a form of language for the Incas.
B. It explains why researchers are having a hard time understanding khipu.
C. It provides evidence to support the idea that khipu have phonetic symbols.
D. It describes what each of the parts of a khipu meant for the Incas.