Compared to viewing a distant object, a human viewing an object held within five centimetres of the eye requires a lens that ________.
A) has been flattened, as a result of contraction of the ciliary muscles
B) has been made more spherical, as a result of contraction of the ciliary muscles
C) has been flattened, as a result of relaxation of the ciliary muscles
D) has been made more spherical, as a result of relaxation of the ciliary muscles

Question

Quizplus · Accepted Answer

When viewing an object held within five centimetres of the eye, the ciliary muscles contract to increase the curvature of the lens, making it more spherical. This allows for greater refraction of light, which is necessary for focusing on objects closer to the eye. Therefore, the correct choice is B.

Compared to Viewing a Distant Object, a Human Viewing an Object