I just came across the question underneath that is in a SCRUM pre exam of Scrum.org itself.
When I read the scrum guide which is the only official document about SCRUM it says explicitly that a Sprint can not be longer than one month.
The answer of the question underneath says al answers apply!
' a' and 'c' doesn't say that is can't be longer than one month. They don't say anything about time..
I hope srum.org can give me a satisfied answer.
19.The length of a Sprint should be?