Answer:
The answer is - A. 1 in. : 3.6 ft.
Explanation:
In order to get the scale on the blueprint we just have to divide the measure in real time by the number of the blueprint, if we know that there´s a wall that is 21.6 feet long, and in the blue print is 6 inches long we just divide it:
scale: 21.6/6
scale: 3.6
So, now we know that for every inch in the blueprint there has to be 3.6 feet on the real construction.
(I hope I helped you)