Final answer:
To find the top of an image formed by a lens, two critical rays are used: the first is parallel to the principal axis, and the second passes through the center of the lens. These rays converge at the point where the image is located. The correct answer is option C.
Step-by-step explanation:
To locate the top of an image formed by a lens when an object with its base resting on the principal axis is placed in front of it, we use two specific rays traced from the top of the object. The first ray travels parallel to the principal axis of the lens and then bends through the focal point on the other side of the lens after passing through it. This is due to the focusing property of lenses for parallel rays, which is a fundamental concept in ray tracing. The second ray that can be traced to locate the image is the one that passes through the center of the lens. The ray that passes through the center of the lens continues in a straight line without deviating, since it strikes the lens at the optical center where no refraction occurs.
Together, these rays will converge (or appear to converge in the case of a virtual image) at the point where the image of the top of the object is formed. By extending these rays to the other side of the lens, they should intersect at the same point, indicating the location of the image. Thus, the correct option for tracing the rays is option C: A ray parallel to the axis and a ray through the center of the lens.