The graph gives the number of farms in the United States from 1850 to 2000. y 7000 6000 5000 4000 3000 2000 1000 X 1860 1900 1940 1980 (a) Estimate the average rate of change in the number of farms between 1850 and 1910 and between 1950 and 1990. (Round your answers to the nearest whole number). 1850 and 1910 farms per year 1950 and 1990 farms per year (b) In which decade did the number of farms experience the greatest average rate of decline? O 1870 - 1880 O 1910 - 1920 1940 - 1950 1950 - 1960 1960 - 1970