The human eye is like a camera that has a lens with:

The human eye operates as a sophisticated optical instrument with dynamic components, making Option D the correct choice.

• Variable Focal Length: Unlike a standard camera lens that moves back and forth to focus, the eye uses accommodation. The ciliary muscles change the curvature and thickness of the crystalline lens. By altering the lens shape, the eye adjusts its focal length to form sharp images of objects at varying distances on the retina.
• Variable Aperture Size: The iris acts as a diaphragm that regulates the size of the pupil. The pupil serves as the aperture of the eye; it constricts in bright light to prevent overexposure and dilates in low light to allow more light to enter. This mechanism ensures optimal image quality under different lighting conditions, similar to the adjustable aperture in a camera.