To find the transformation which doesn't preserve congruence:
Let us consider option a.
Here, it is given that,
[tex](x,y)\Rightarrow(\frac{1}{7}x,\frac{1}{7}y)[/tex]
Since it has the scale factor
[tex]\frac{1}{7}[/tex]
So, the type of transformation that occurred is the dilation transformation.
Hence, this transformation preserves similarities but doesn't preserve congruence.
Thus, the correct option is a.
