To determine how a hollow prism filled with water will affect the deviation of incident rays when placed in air, we need to consider the principles of refraction and the geometry of the prism. When light passes through a prism, it undergoes refraction, which is the bending of light due to a change in speed as it moves from one medium to another. For a given material, the amount of bending depends on the refractive index of the material and the angle at which the light enters the material. A hollow prism filled with water has its faces made of a material with a refractive index different from water. When the prism is placed in air, the light will encounter two refractions: once when it enters from air into water and once when it exits from water into air. The bending effect is determined by the difference in refractive indices between air and water. Typically, the refractive index of water is higher than that of air (water's refractive index is about 1.33 , while air's is approximately 1.00 ). This means that when light enters the water from air, it bends towards the normal, and when it exits back into the air, it bends away from the normal. The overall path of the incident light through the prism will result in a deviation towards the base of the prism. Thus, based on the principles of refraction and the prism's geometry, the correct answer is: Option D: Towards the base