A coin placed in a vessel filled with water appears slightly raised due to the refraction of light, which corresponds to option [B]. Refraction occurs because light travels at different speeds in different mediums, such as water and air. When light passes from water into air (or vice versa), its path bends at the interface due to the change in speed, following Snell’s law. This bending effect causes the coin to appear higher than its actual position when viewed from above the water’s surface. The amount of apparent displacement depends on the refractive indices of water and air and the angle at which the observer views the coin. This phenomenon is a common optical illusion that demonstrates how light behaves when it transitions between materials with different optical densities. Understanding refraction is essential in fields such as optics, astronomy, and underwater exploration, where accurate predictions of light’s behavior in various mediums are critical for scientific observations and practical applications.