Answer:
a. OM is congruent to ON.
Explanation:
To use the HL Theorem, you must have a congruent hypotenuse and a congruent leg. In this case, you have two congruent hypotenuses. You just need to find two congruent legs.
a. OM is congruent to ON. This says that two legs are congruent, so this is your answer.
b. LM is congruent to ML. This does not help as it is saying a segment is the same as the same segment.
c. and d. Both of these use angle measurements, which does not help with the HL Theorem.
Hope this helps!