The rural population grew slowly from 1950 to 1990 and reached its peak in 1992.

A. The rural population experienced an upward trend from 1950 to 1992.

B. The rural population hit its highest level in 1992 after a slight increase in 40 years.

C. The rural population leveled off in 1992 after growing slowly for 40 years.

D. The rural population reached its lowest level in 1992 after growing slowly for 40 years.