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

[EX Q]: Presta valves are the skinnier of the _ valve types.
[EX A]: two

[EX Q]: Babies can range in age from newborn up to _ years old.
[EX A]: three

[EX Q]: Cheese makes a remarkable culture medium for bacteria, which stay alive for up to _ months.
[EX A]:
six