The Difference Between the Stretching Ability of Silk and Wool $\alpha$

Multiple Choice

The difference between the stretching ability of silk and wool fibers, low and high ability to stretch, respectively, is due to their protein components. Which statement CORRECTLY attributes the secondary structure contributions to this stretch ability?

A) Both silk and wool fibers have roughly equal distributions of $\alpha$ helices and $\beta$ sheets, but they are arranged in different conformations.
B) Silk is mainly $\beta$ sheets; wool is mainly $\alpha$ helices.
C) Silk is mainly $\alpha$ helices; wool is mainly $\beta$ sheets.
D) Silk contains mainly $\beta$ barrels; wool contains mainly coiled-coil $\alpha$ helices.
E) Silk contains coiled-coil $\alpha$ helices; wool contains mainly $\beta$ barrels.