Zoe is using the figure shown below to prove Pythagorean Theorem using triangle similarity: In the given triangle ABC, angle A is 90° and segment AD is perpendicular to segment BC.

Which of these could be a step to prove that BC2 = AB2 + AC2?
1) by distribution, AC2 plus AB2 = BC multiplied by The quantity DC plus AB
2) by distribution AC2 plus AB2 = BC multiplied by the quantity DC plus BD
3) by distribution AC2 plus AD2 = BC multiplied by the quantity DC plus AB
4) by distribution AC2 plus AD2 = BC multiplied by the quantity DC plus BD