Plzz help me!
The Orbit in London, England, is the world's tallest tube slide. It is as tall as a 25-story building. From the base, _. which is the ground level, an elevator carries people up to the top.
What does "base" mean in this passage?
A.a structure with many floors.
B.the height of something.
C.a place that people visit.
D.the bottom of something.
