Consider the functions P(x)=4sinx, Q(x)=4cosx, and R(x)=−4sinx, each defined for all real x. Exactly one of these can serve as the graph of f, one as f′, and one as f′′ for some twice-differentiable function f. Which labeling is correct?
a) P is f′,\; Q is f,\; R is f′′
b) P is f,\; Q is f′,\; R is f′′
c) P is f′,\; Q is f′′,\; R is f
d) P is f,\; Q is f′′,\; R is f′