In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[Q]: Presta valves are the skinnier of the _ valve types.
[A]: two


[Q]: Acrobats mount a single bicycle until _ people in all are stacked on top of it.
[A]: ten


[Q]: Most females are sexually mature at about five to _ years.
[A]:
six