The author has used American Indian languages as an example to show that they are_________

The author has used American Indian languages as an example to show that they are__________．

A.just as old as some well-known languages

B.just as sophisticated as some well-known languages

C.more developed than some well-known languages

D.more complex than some well-known languages

请帮忙给出正确答案和分析，谢谢！