Solve the Problem $1 \mathrm{yr}$ On a Fixed Principal Varies Directly as the Interest Rate

Multiple Choice

Solve the problem.
-The interest I earned in $1 \mathrm{yr}$ on a fixed principal varies directly as the interest rate $\mathrm{r}$ . An investment earns $\$ 25.38$ at an interest rate of $3.55 \%$ . Find an equation of variation.

A) $\mathrm{I}=-\frac{355}{2538} \mathrm{r}$
B) $\mathrm{I}=\frac{2183}{100} \mathrm{r}$
C) $\mathrm{I}=\frac{2538}{355} \mathrm{r}$
D) $\mathrm{I}=\frac{355}{2538} \mathrm{r}$