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

[EX Q]: Reds mature well for six to _ years.
[EX A]: eight

[EX Q]: Frozen grafts can have a shelf life of up to _ years.
[EX A]: five

[EX Q]: Cows give birth every three to _ years.
[EX A]:
five