Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Monatomic ions form when a single atom gains or loses electrons.
What form when a single atom gains or loses electrons?

The action of flushing the toilet, performed multiple times daily, is the single biggest use of water in the home.
What action, performed multiple times daily, is the single biggest use of water in the home?

Limiting the number of cars on the roads would most likely improve the air quality in large texas cities.

Which of these would most likely improve the air quality in large Texas cities?