Does the new Spring length need to be agreed by the Product Owner if a SCRUM Team decide to revise it?

In a Retrospective, a Scrum Team decides to revise the Sprint length. The new Sprint length needs to be agreed by Product Owner.

I think the answer should be No. Because the questions says ".... a Scrum Team decides.....". TheProduct is part of a Scrum Team, so if a Scrum Team decides he/she (Product Owner) already agreed! So it is not necessary to have an "extra" agreed from the Product Owner.

Yes

The Product Owner needs to ensure that it is short enough to limit business risks and also short enough so the team can synchronize the development work with other business events. Please note that the finalized Sprint Length cannot be longer than 1 calendar month. Correct answer is A