Show and Tell

Here's a question from the Sample Practice Forestry Test, Arkansas Envirothon:

"The growths, on the roots of a cypress tree, that protrude above the surface of the ground or the water in which it is growing are referred to as _____.

A. cloroplasts B. gallinues C. coniferous D. knees"

Can you answer it?

If you chose D, you were correct. See them in the water, around the cypress tree?