economic trends in china's gross domestic product over a 50 year period can best be described as

a. a gradul but steady decline in economic activity
b. relatively stable with low levels of economic activity from the 1950s to the late 1990s
c. a gradual but steady increase in economic activity
d. intially stable with a drastic increase in economic activity starting in the late 1980s

d. initially stable with a drastic increase in economic activity starting in the late 1980s