1. **Stating the problem:** A body of weight $W$ rests on an inclined plane that makes an angle $\theta$ with the horizontal. We want to find the component of the weight perpendicular (normal) to the plane. 2. **Analyzing the forces:** The weight $W$ acts vertically downwards. To find its component perpendicular to the inclined plane, we drop a perpendicular from the weight vector onto the plane's normal axis. 3. **Using trigonometry:** The angle between the weight vector (vertical) and the direction perpendicular to the inclined plane is $\theta$ since the incline makes angle $\theta$ with the horizontal. 4. **Component calculation:** The component of $W$ perpendicular to the incline is given by $$W \cos \theta$$ because the weight vector forms angle $\theta$ with the normal to the plane. 5. **Answer:** The correct choice is (b) $W \cos \theta$. **Final answer:** The weight component perpendicular to the plane is $W \cos \theta$.