The graph of the accompanying figure shows the average annual percentage change y = f(t) in a particular country's gross national product (GNP) for the years 1978-1983. Ay (%) 10- 8- 1978 1979 1980 1981 1982 Year 1983 G dy Choose the correct graph of dt O A. OB. Ay' 10- 10- a Q 1978 1983 1978 1983 G G -10- -10 C. OD. 10- 10- 1978 1963 E 1976 1983 -10 -10-