PLEASE help me understand this!

2. Heapsort tracing. For the set of numbers {1,2, 3,5,6, 7), which input elicits the (exact) best/worst case for the Heapsort algorithm presented in class? (Here, the sole measure of (exact) complexity is the (exact) number of comparisons made throughout the execution of the algorithm-which includes building the max-heap.) For each case, give the sequence of comparisons made, and the total. (10 points) best: 12c example: (7,3, 6, 1, 2,5) worst: 17c example: (6, 2, 3, 1,7,5)