A solid cylinder of mass $M$ and radius $R$ rolls without slipping down an inclined plane making an angle $\theta$ with the horizontal. Then its acceleration is
(a) $\frac{1}{3} g \sin \theta$
(b) $\frac{2}{3} g \sin \theta$
(c) $\frac{2}{5} g \sin \theta$
(d) $\frac{2}{7} g \sin \theta$