Answer: The correct option is (A). 3.
Step-by-step explanation: We are given to find the scale factor of dilation from ΔABC to ΔDEF.
As shown in the figure, the lengths of the sides of ΔABC to ΔDEF are
AB = 5 units, BC = 4 units, CA = 3 units,
DE = 15 units, EF = 12 units, FD = 9 units.
We know that the scale factor is given by

Therefore, the scale factor of dilation from from ΔABC to ΔDEF is

Thus, the required scale factor is 3.
Option (A) is correct.