13. Lichens and mosses are the first organisms to grow
in an area. Over time, grasses and shrubs will grow
where these organisms have been. The grasses and
shrubs are able to grow in the area because the lichens
and mosses
A. synthesize food needed by producers in the area
B. are at the beginning of every food chain in a
community
make the environment suitable for complex plants
(D. provide the enzymes needed for plant growth