What fabric was used for underwear in the early 20th century?

In the early 20th century, underwear was primarily made from cotton, linen, or wool. Cotton was the most common fabric used, as it was breathable, absorbent, and relatively inexpensive. Linen was also popular, as it was strong and durable. Wool was used for warmth, but it was less common due to its higher cost and tendency to irritate the skin.