D. 1
Explanation:
A scale factor is a number that multiplies (" scales ") a quantity.
It means to find it you need to divide the dimension of the new shape by the original shape
Here:
New shape UVW
Originale shape RST
UW / RT = 7/ 7 = 1
VW / ST = 7/7 = 1
UV / RS = 8 / 8 = 1
====> UVW / RST = 1
The scale factor is 1
