Given the two circles shown in the exercise, you need to remember that, by definition, two figures are congruent when they have the same size and they have the same shape.
In this case, you can identify that the circles have the same diameters (remember that a diameter of a circle is the length that passes through the center of the circle and touch two points on the circumference):
[tex]\begin{gathered} d_1=2units \\ d_2=2units \end{gathered}[/tex]Therefore, these circles have the same shape and size.
By definition, two figures are similar when their corresponding angles are congruent and the ratios of the corresponding sides are proportional.
In this case, since the figures are circles, you know that they both measure 360 degrees. Knowing that they also have the same diameter, you can determine that they are similar too.
Hence, the answer is: They congruent and similar.