300 to 350 mm
400 to 450 mm
500 to 550 mm
600 to 650 mm
Answer is Right!
Answer is Wrong!
The correct answer is: C. 500 to 550 mm.
The sum of the tread and rise of a stair must lie between 500 and 550 mm. This is to ensure that the stair is comfortable and safe to use. If the tread is too small, it will be difficult to take a step and you may trip. If the rise is too high, it will be difficult to lift your leg and you may also trip. The ideal range for the sum of the tread and rise is 500 to 550 mm, as this allows for a comfortable and safe walking experience.
Option A
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