Question

the orbit slide in london, england
the orbit in london, england, is the worlds 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.
which of these clues helps you
understand what \base\ means?

Explanation:

The text "From the base, which is the ground level, an elevator carries people up to the top." directly explains that "base" is related to the starting point (ground level) from which the elevator ascends. This context - clue helps in understanding the meaning of "base".

Answer:

The clue "From the base, which is the ground level, an elevator carries people up to the top." helps understand what "base" means.