Given a scientific passage and an answer, generate a question for the given answer.

Passage: The surface seismic waves do the most damage because they only travel along the surface of the ground. Answer: surface
What type of seismic waves do the most damage?

Passage: Figure 43.17 Rising and falling hormone levels result in progression of the ovarian and menstrual cycles. (credit: modification of work by Mikael Haggstrom). Answer: hormones
Rising and falling levels of what will result in progression of the ovarian and menstrual cycles?

Passage: The liver secretes bile acids. Bile acids help digest fat. Some liver bile is secreted directly into the small intestine. Answer: fat
What does bile help to digest ?