This WitCH come courtesy of a smart VCE student. It concerns the newly instituted VCE subject of Algorithmics, and comes from the 2017 exam:
The Examiners’ Report indicates that half of students gave the intended answer of A, and notes
It is important for students to understand that Big-O notation describes an upper bound, and so is only used for analysis of worst-case running times.
Have fun.