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

[EX Q]: Reverse osmosis uses three to ten gallons of water to produce _ gallon of drinking water.
[EX A]: one

[EX Q]: Allergic rhinitis is the most common allergic disease, with one in _ Canadian adults affected.
[EX A]: five

[EX Q]: Cleavage is poor in _ directions.
[EX A]:
two