If want a direct answer it would be the decrease in mice, but if you want to get technical the decrease in grain spills caused mice to leave so that would be the indirect cause
Plants need this waxy outer coating, also known as a cuticle, for a
variety of reasons. The cuticle keeps the important things the plant
needs in, such as water and carbon dioxide, and the things the plant
doesn't need, such as too much heat, out. It performs a few different
functions, including protecting the important cells needed for
photosynthesis.
D because no human has the ability to make their own food within themselves.
