For small oscillations, a simple pendulum can be modeled as simple harmonic motion. Suppose angular displacement θ is defined to be positive when the bob is displaced clockwise from the lowest point. Which of the following statements about the restoring torque τ exerted on the pendulum bob is most consistent with this choice of coordinate system?
(a) τ is negative and proportional to θ.
(b) τ is positive and proportional to θ.
(c) τ is negative and proportional to sinθ.
(d) τ is negative and independent of θ.