When confined to the reservations, Plains Indians recorded their past exploits and history in which medium?

A) Blankets
B) Shields
C) Ledger books
D) Beaded leather

Plains Indians, when confined to reservations, adapted to the available resources and began using ledger books to record their history and stories. This was a shift from their traditional methods of storytelling and record-keeping, such as oral histories and symbolic representations on items like tipis, clothing, and shields. Ledger art became a significant form of expression, documenting their experiences, battles, and daily life during a period of great change and hardship.