The answer that correctly fills in the blank in Statement 2 to complete the proof is option 3.
The correct choice to fill in the blank in Statement 2 is option 3: ∠C≅∠E.
Congruent angles refer to angles that have the same measure, sharing an equal degree of rotation. In geometric terms, if two angles are congruent, their corresponding sides are in one-to-one correspondence, and the angles can be superimposed perfectly. This equality in measurement signifies identical geometric properties, emphasizing that the angles possess the same angular extent.
Therefore, option 3 is the correct choice for a valid and coherent proof.