Eye structures that refract light onto the retina Steps:

• Identify main refractive structures in the eye: cornea and lens.
• Cornea provides initial fixed refraction of incoming light.
• Lens adjusts focus via accommodation for near/far objects.
• Confirm P as cornea and R as lens based on standard anatomy.

Why B is correct:

• Cornea (P) and lens (R) are the primary refractors that bend light rays to converge precisely on the retina, per Snell's law of refraction.

Why the others are wrong:

• A: Q (likely iris) controls light entry but does not focus rays.
• C: Q (iris) and R (lens) omit cornea's essential initial refraction.
• D: Q (iris) and S (likely retina) involve detection, not focusing.

Final answer: B