An increasing function f satisfies f(10) = 5 and f'(10) = 8. Which of the following statements about the inverse of f must be true? A. (f^-1)'(5) = 10 B. (f^-1)'(8) = 10 C. (f^-1)'(5) = 8 D. (f^-1)'(5) = 1/8