What is the degree measure of the acute angle formed by lines with slopes $2$ and $\tfrac{1}{3}$? $\textbf{(A)}~30\qquad$ $\textbf{(B)}~37.5\qquad$ $\textbf{(C)}~45\qquad$ $\textbf{(D)}~52.5\qquad$ $\textbf{(E)}~60$