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One end of a string of negligible mass is wrapped around a pulley and the other end is connected to a hanging block of mass $m$. A motor exerts a torque of magnitude $\tau$ on the pulley and causes it to rotate in the clockwise direction, lifting the block. The radius of the pulley is $R$ and the rotational inertia of the pulley is $I$. Which of the following equations accurately represents this scenario and could be used to solve for the angular acceleration $\alpha$ of the pulley? (A) $\tau-m(\alpha R-g) R=I \alpha$ (B) $\tau-m(\alpha R+g) R=I \alpha$ (C) $\tau-m \alpha R^{2}=I \alpha$ (D) $\tau+m \alpha R^{2}=I \alpha$