Study the graph of changes in the cost of living between 1970 and 1973. A line graph titled Changes in U S Cost of Living from 1970 to 1973. The x-axis is labeled Date of Measurement from January 1970 to September 1973. The y-axis is labeled Rate of Inflation (percent) from 0 to 6. In January 1970 the rate of inflation was over 6 percent. In May 1971 the rate of inflation was 5 percent. In May 1972 the rate of inflation was 3 percent. In January 1973 the rate of inflation was under 3 percent. In September 1973 the rate of inflation was almost 5 percent.

Which statement best describes what caused this change?