Correct option is (c) f is continuous on [a,a+h]
The best I can explain: According to Rolle’s theorem, if f : [a,a+h] → R is a function such that
i) f is continuous on [a,a+h]
ii) f is differentiable on (a,a+h)
iii) f(a) = f(a+h) then there exists at least one θ c ∈ (0,1) such that f’(a+θh) = 0