Final answer:
The line segment congruent to HF is CD.
Step-by-step explanation:
To determine which line segment is congruent to HF, we need to analyze the given information. The centers of the three circles are labeled as A, B, and C. We can see that HF is a line segment connecting the centers of the circles, and it is perpendicular to AB. Therefore, the line segment congruent to HF would be CD (option b), as it is also perpendicular to AB.