What is the slope of the line tangent to the graph of fat (a, f(a))? Which of the following is the correct formula for the slope of the tangent line? f(b) - f(t) O A. man = lim - b-t t-a f(t) - f(a) O B. mtan = lim t- a t-a f(b) + f(t) O c. mtan = lim b-t t-a f(t) + f(a) O D. mtan = lim t- a t-a