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

[EX Q]: Morocco has _ perennial rivers and many dams have been built with potential for power generation.
[EX A]: four

[EX Q]: House wrens are small birds, four and a half to _ and a four inches in length.
[EX A]: five

[EX Q]: Woodchucks can dig up to three entrances to _ den.
[EX A]:
one