Answer:
He is incorrect because the scale factor is 1/3.
Explanation:
we know that
If two triangles are similar, then the ratio of its corresponding sides is proportional and this ratio is called the scale factor
In this problem
Triangles CA'B' and CAB are similar
The pre-image is the triangle CAB
The image is the triangle CA'B'
therefore
The scale factor is equal to
CB'/CB
we have
CB'=2 units
CB=2+4=6 units
substitute
CB'/CB=2/6=1/3
therefore
He is incorrect because the scale factor is 1/3.