The rental agencies determine the rules for that. Most rental companies will not rent to anyone under the age of 25. Some will rent to people 21 to 24 years old, but charge a premium rate. The only time I have ever heard of a rental car company renting to an 18-year old is to a member of the military.
1 The lens is a soft, transparent, spherical structure that is suspended within the eye, just behind the pupil. 2  The lens is responsible for focusing light coming in through the pupil onto the retina in the back of the eye.
The pupil of the eye is actually just an opening to the eye that leads to the lens; no color is possessed by the pupil itself. We see black when we look into the pupil because light that is accepted into the area is fully absorbed by the eye tissues on its way to the retina.