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

Q: Morocco has _ perennial rivers and many dams have been built with potential for power generation.

A: four
****
Q: Most divorces take place after three to _ years of marriage.

A: five
****
Q: Brain death occurs in just _ to six minutes unless the heart rhythm is restored.

A:
four
****