Based on the data in Chart 1, under what situation would Mr Chan have gained from July 1999 to July 2000?
A. Before the period of time he had already borrowed a sum of money from a bank at a fixed interest rate.
B. His salary remained unchanged during that period of time.
C. He adjusted the rental charge to his tenant in a rental property according to the change in price level.
D. He had a collection of antique vases