If R(t)represents the Rate at Which a Country's Debt Is $\frac{r(2000)-r(1990)}{2000-1990}$

Multiple Choice

If r(t) represents the rate at which a country's debt is growing, then the increase in its debt between 1990 and 2000 is given by

A) $\frac{r(2000) -r(1990) }{2000-1990}$
B) $r(2000) -r(1990)$
C) $\frac{1}{10} \int_{1990}^{2000} r(t) d t$
D) $\int_{1990}^{2000} r(t) d t$
E) $\frac{1}{10} \int_{1990}^{2000} r^{\prime}(t) d t$