Note that m ∠ a means the measure of the angle a. With that notation you can write:
∠1 and ∠2 suplementary => m ∠1 + m ∠2 = 180°
∠1 and ∠3 suplementary => m ∠1 + m ∠3 = 180°
∠2 and ∠3 are corresponding and a || b => m ∠2 = m ∠3
=> m ∠2 = m ∠3 => ∠2 and ∠3 are congruent angles, which means that they have same shape and same size (measure)..
The notation for congruency is the equal sign = with the line ~ above it.
So, the answer is the second option.
