Answer:
Option B is not necessarily true.
Explanation:
Option A.
AD =

Since triangle ABC is reflected to form triangle

So distance AD may be equal to distance
. So this option is true.
Option B.
=

This statement is not correct because
≠

Option C.
m∠ACB = m∠

Since translated triangle
and ΔABC are similar.
So the statement is true.
Option D.
m∠BAC = m∠

Since translated triangle
and ΔABC are similar.
So the statement is true.
Therefore, option B is not necessarily true.