18. Identify which of the following describes the term parallax. A. the apparent movement of closer objects compared to distant objects B. the apparent movement of closer objects due to the viewer's change in position C. the change in image between a viewer and a distant object D. the change in size between a closer object and a distant object

The correct answer is **B. the apparent movement of closer objects due to the viewer's change in position.**<br /><br />Parallax is the observed shift in an object's apparent position against a background when viewed from two different locations. The closer the object, the greater the apparent shift. Option A is close, but doesn't explicitly mention the viewer's movement which is key to the concept of parallax. Option C describes a change in image, but not necessarily due to parallax. Option D describes a change in size, which is related to perspective, not parallax.<br />