"Some plants called epiphytes, or air plants, have adapted to get nutrients from the air.
Some examples of epiphytes in rainforests are mosses, lichens, and orchids. Although
they often live on other plants, they don't take any nutrients from the other plants-they
get what they need straight from the air with special root systems.
There are also some plants called parasitic plants. They grow on other plants, their host
plants. Parasitic plants actually DO take nutrients from their host plants."

Why might the author have capitalized the word "DO"?
A. to point out a similarity
B. to make a contrast
C. to summarize a process
D. to make an argument