Answer:
C. dialtion
Step-by-step explanation:
A dialtion either reduces or enlarges the dimensions of a shape, causing for them to no longer be congruent.
A reflection wouldn't change the congruency of the shape since it is just reflecting it across whatever axis. The dimensions stay the same.
A rotation would simply rotate/turn the shape. The dimensions would not be changed.
A translation would slide the shape elsewhere whether it be vertically, horizontally, or diagonally. The dimensions would not change.
Therefore, we can conclude that option C makes the most sense.
hope this helps!
