The local linear approximation of a function f will always be less than or equal to the function's value if, for all x in an interval containing the point of tangency:

a. f' > 0

b. f' < 0

c. f" > 0

d. f" < 0

e. f' = f" = 0

I have no idea what the answer is so I'd appreciate it if someone could please give me a detailed explanation.