Answer:
A. 1
Step-by-step explanation:
Scale Factor:
The scale factor is the number you multiply the length of a side of the first triangle to get the length of the corresponding side of the other triangle.
Every side that measures 5 in triangle ABC has a corresponding side in triangle DEF that also measures 5. In this case 5 * 1 = 5, so the scale factor is 1.
Answer: A. 1
