AHSME 1950 Problem 11

If in the formula $C =\frac{en}{R+nr}$, where $e$, $n$, $R$ and $r$ are all positive, $n$ is increased while $e$, $R$ and $r$ are kept constant, then $C$: $\textbf{(A)}\ \text{Increases} \textbf{(B)}\ \text{Decreases} \textbf{(C)}\ \text{Remains constant} \textbf{(D)}\ \text{Increases and then decreases} \\ \textbf{(E)}\ \text{Decreases and then increases}$