What is the formula for Lagrange’s theorem?

• A. f’(c) = \(\frac {f(a)+f(b)}{b-a}\)
• B. f’(c) = \(\frac {f(b)-f(a)}{b-a}\)
• C. f’(c) = \(\frac {f(a)+f(b)}{b+a}\)
• D. f’(c) = \(\frac {f(a)-f(b)}{b+a}\)