Question

Seth is using the figure shown below to prove Pythagorean Theorem using triangle similarity:

In the given triangle ABC, angle A is 90o and segment AD is perpendicular to segment BC.
Which of these could be a step to prove that BC2 = AB2 + AC2?

By the cross product property, AB2 = BC multiplied by BD.

By the cross product property, AC2 = BC multiplied by BD.

By the cross product property, AC2 = BC multiplied by AD.

By the cross product property, AB2 = BC multiplied by AD.
I think it might be B but I need some help understanding this.