What is the missing statement in the proof?

it's B! because it's what was already given to you next to the picture, and it just wanted you to rewrite it into the proof
Answer:
B: ∠1 ≅ ∠2
Step-by-step explanation:
Transitive property of congruence says that
If a=b and a=c then b=c
From the given we can see that ∠1 ≅ ∠2
Vertical angles are congruent. so ∠1 ≅ ∠3
By Transitive property of congruence
If ∠1 ≅ ∠2 and ∠1 ≅ ∠3 then ∠3 ≅ ∠2
The missing statement in the proof is the statement already given for the diagram that is
∠1 ≅ ∠2