A building has z floors. The number of apartments on each floor is 6 less than the number of floors. The number of rooms in each apartment is 1 less than the number of apartments on each floor. The expression below shows the total number of rooms in the building:
z(z - 6)(z - 7)
Part A: What does z(z - 6) represent? (4 points)
Part B: What type of polynomial is z(z - 6)(z - 7)? (3 points)
Part C: What is the degree of the polynomial z(z - 6)(z - 7)?