TASK DEFINITION: In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
PROBLEM: Prolactin exists in _ heterogenic forms which possess varying biological activity.

SOLUTION: three

PROBLEM: Some species bear living offspring only every _ to five years.

SOLUTION: three

PROBLEM: Calves grow quickly and are weaned from their mothers in only three to _ months.

SOLUTION:
four