Your question is Variance vs Trend Analysis. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You are reviewing monthly financial results and see that one cost center had a large swing in a single month, while another has been drifting upward for several quarters. You need to explain how to separate a one period variance from a longer term trend.
Can you explain the difference between variance analysis and trend analysis?