Final answer:
The correct sequence to prove that AD = BC is to first prove ABC congruent to ACDA and then state that AD and BC are corresponding sides of the triangles.
Step-by-step explanation:
The correct sequence that could be used to prove that AD = BC is option A) First prove ABC is congruent to ACDA, and then state AD and BC are corresponding sides of the triangles.
In this option, we prove that triangle ABC is congruent to triangle ACDA. This allows us to conclude that AD and BC are corresponding sides of the triangles, meaning they are equal in length.