The correct Answer is 25 cm
Explanation
The question pertains to the standard physiological characteristic of the human eye related to vision clarity.
The least distance of distinct vision, also known as the near point, is the minimum distance at which an object can be seen clearly and distinctly without any strain on the eye. This is a fundamental concept in human optics.
Statement-wise Analysis
The question asks for a specific value, not a set of statements. Therefore, a direct analysis of the options is provided.
- 10 cm - Incorrect. This distance is typically too close for a normal human eye to focus clearly without strain.
- 25 cm - Correct. For a normal human eye, the least distance of distinct vision is approximately 25 cm. At this distance, the ciliary muscles are maximally contracted, and the eye lens has its shortest focal length, allowing for clear focus.
- 50 cm - Incorrect. While objects at 50 cm can be seen clearly, it is not the least distance of distinct vision.
- 100 cm - Incorrect. Similar to 50 cm, this is not the least distance for distinct vision.
Key Takeaway: The standard least distance of distinct vision for a normal human eye is 25 cm.