Final answer:
Virtual and real images can appear tilted, higher, or lower than they are due to phenomena such as refraction of light and the properties of mirrors and lenses. Objects can seem closer in certain mirrors and shallower in water due to refraction, which bends light as it passes through different mediums.
Step-by-step explanation:
The filled in blank for the statement "_________objects are tilted, higher or lower than they actually are" should be virtual images for options (a) and (b), and real images for (c) and (d). When looking at mirrors, objects can appear closer than they actually are due to the type of mirror being used and the effect known as Essential Knowledge 6.E.2. In the case of clear mountain streams, objects appear shallower than they actually are because of refraction of light, which bends the light away from the normal at the interface between water and air, causing the image to appear at a location that is above the actual position of the object.
Similarly, when we observe an object through a glass of water, refraction occurs, causing the object to appear distorted because light bends as it passes through different mediums with varying densities. The phenomenon of tidal distortion also plays a role in how objects are perceived, but it is typically too insignificant to affect solid objects on Earth's surface. Lastly, the apparent size of an object is determined by the angle it subtends from the eye. Objects that subtend larger angles appear larger because they form larger images on the retina.