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

[EX Q]: Pups consume an average of _ liters of milk a day .
[EX A]: eight

[EX Q]: White sturgeon inhabit _ large river systems, all on the western coast of North America.
[EX A]: three

[EX Q]: Cancer is the number _ killer behind heart disease.
[EX A]:
two