Which hair shape is round in cross section?

The correct answer is that the hair shape that is round in cross section is associated with the American Indian. Round cross sections typically indicate hair that is straighter and smoother in texture. This characteristic aligns with the general understanding of hair types found among American Indian populations, which often exhibit such traits.

Understanding hair structure is important in fields like aesthetics and cosmetology, as the shape of hair can influence both its texture and how it responds to various treatments, such as waxing, cutting, and styling. Other hair types may exhibit different cross-sectional shapes, which can result in diverse textures and styling challenges, but the round cross section is notably characteristic of the hair found among American Indian populations.