Given the right triangle below, use the cosine function to write a trigonometric expression for the missing angle $\phi$.

• A. $\phi=\cos^{-1}\left(\frac{12}{13}\right)$
• B. $\phi=\cos^{-1}\left(\frac{13}{5}\right)$
• C. $\phi=\cos^{-1}\left(\frac{13}{12}\right)$
• D. $\phi=\cos^{-1}\left(\frac{5}{13}\right)$