The least distance of distinct vision is (cms.)

The correct answer is (a) 25.

The least distance of distinct vision is the closest distance at which an object can be placed in front of the eye and still be seen clearly. It is typically about 25 cm for a person with normal vision.

Option (b) is incorrect because 5 cm is too close for the eye to focus on an object. Option (c) is incorrect because 75 cm is too far for the eye to focus on an object. Option (d) is incorrect because 100 cm is too far for the eye to focus on an object.