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

[EX Q]: Optical isomers differ in the arrangement of _ groups around a chiral carbon.
[EX A]: four

[EX Q]: Many Asian countries deny entry to travelers whose passports are valid for less than _ months.
[EX A]: six

[EX Q]: Female devils are occupied with raising their young for all but approximately _ weeks of the year.
[EX A]:
six