If height of the first storey of a building is 3.2 m and riser is 13 cm, the number of treads required, is A. 12 B. 18 C. 24 D. 25

The correct answer is C. 24.

To calculate the number of treads required, we divide the height of the storey by the height of the riser. The height of the storey is 3.2 m, and the height of the riser is 13 cm, so the number of treads required is 3.2 m / 0.13 m = 24.

Option A is incorrect because 12 is not a factor of 3.2.

Option B is incorrect because 18 is not a factor of 3.2.

Option D is incorrect because 25 is not a factor of 3.2.