A carpenter’s sketch of a room does not include a scale. She measures a wall that has been built and finds that it is 51.2 feet long. On the blueprint, this wall is 8 inches long. What is the scale for this blueprint?
A. 1 in. : 6.4 ft.
B. 1 in. : 64 ft.
C. 1 in. : 408 ft.
D. 1 in. : 409.6 ft.