4. The transparent front part of the eye that helps focus light is the: a) Pupil b) Iris c) Cornea d) Vitreous humor.

## Step 1<br />The question is asking for the part of the eye that is transparent and helps focus light. The options provided are the pupil, iris, cornea, and vitreous humor.<br /><br />## Step 2<br />The pupil is the black circular opening in the center of the iris that allows light to enter the retina. It does not focus light.<br /><br />## Step 3<br />The iris is the colored part of the eye that controls the size of the pupil and thus the amount of light that enters the eye. It does not focus light.<br /><br />## Step 4<br />The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. It plays a key role in focusing light onto the retina.<br /><br />## Step 5<br />The vitreous humor is a clear, jelly-like substance that fills the space between the lens and the retina. It does not focus light.