BOTANISTS! whats a Rhizome exactly? what about a Stolon?

Question

these questions were in a quiz i had. If you can, tell me which answer goes with which:

1. a modified above ground stem

2. a modified medium ground stem

3 a modified underground stem

4. a modified ground stem.

I really cant tell the difference between medium ground stem and just ground stem. could someone explain that?

Answer 1

Yeah thats really weird.  A rhizome is a modified stem that usually grows below ground.  Stolon are similar, but generally grow above ground.  I have no idea what medium ground is either.  Must just be a filler answer.