Consider the following statements in the context of human eye :
(a) The diameter of the eye ball is about 2.3 cm.
(b) Iris is a dark muscular diaphragm that controls the size of the pupil.
(c) Most of the refraction for the light rays entering the eye occurs at the crystalline lens.
(d) While focusing on the objects at different distances the distance between the crystalline lens and the retina is adjusted by ciliary muscles.
The correct statements are –
Generated by claude-sonnet-4-6 · 2026-06-15 06:53 · grounding rag
Model Answer
(A) (a) and (b)
Wait — re-checking: Statement (a) ✓ (diameter ~2.3 cm), (b) ✓ (iris is a dark muscular diaphragm), (c) ✗ (most refraction occurs at the cornea, not the crystalline lens), (d) ✗ (ciliary muscles change the curvature/focal length of the lens, not the distance between lens and retina).
Correct answer: (A) (a) and (b)
Explanation
- The passage explicitly states: "Most of the refraction for the light rays entering the eye occurs at the outer surface of the cornea" — so statement (c) is wrong.
- Statement (d) is wrong because in the human eye the lens-to-retina distance is fixed; it is the focal length (via curvature change by ciliary muscles) that adjusts, not the distance itself.
- Statements (a) and (b) are directly confirmed by the passage, making (A) the correct choice.