TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Transient pseudopodia are temporary feet that protists have called.

SOLUTION: What are temporary feet that protists have called?

PROBLEM: When light passes from one medium to another, it changes speed.

SOLUTION: When light passes from one medium to another, it changes what?

PROBLEM: Ash that enters the air naturally as a result of a volcano eruption is classified as a primary pollutant.

SOLUTION:
Ash that enters the air naturally as a result of a volcano eruption is classified as what kind of pollutant?