Answer: the correct option is (C) The lines are parallel.
Step-by-step explanation: Given that ∠1 ≡ ∠5 in the figure shown.
We are to describe the relationship between the lines a and b.
From the figure, we see that
the lines a and b are cut by a transversal, where ∠1 and ∠5 are corresponding angles.
Since the corresponding angles are congruent, so the measure of the corresponding angles are equal.
i.e., m∠1 = m∠5.
Therefore, the lines a and b are parallel.
Thus, (C) is the correct option.
