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

[EX Q]: Melanocytes are dendritic and are distributed roughly _ per six basal cells.
[EX A]: one

[EX Q]: Perennial grass takes _ to five years before it is mature enough to produce adequate seed.
[EX A]: three

[EX Q]: Probability is a concept governed by _ basic axioms.
[EX A]:
three