Diana and joby wrote the following proofs to prove that vertical angles are congruent. who is correct?

diana's proof

statement justification

∠1 + ∠2 = 180° definition of supplementary angles

∠1 + ∠4 = 180° definition of supplementary angles

∠1 + ∠2 = ∠1 + ∠4 transitive property of equality

joby's proof

statement justification

∠2 = ∠4 vertical angles are congruent.

∠1 = ∠3 vertical angles are congruent.

vertical angles are congruent. vertical angle theorem

a. diana is correct, but joby is not.
b. both diana and joby are correct.
c. neither diana nor joby is correct.
d. joby is correct, but diana is not.