Move point B some more. As you move point B, the angle formed between AB and CD varies. If you want to make AB perpendicular to CD what do you need to do?

The correct answer is -4

The question is kind of confusing. if it's asking how many variations of answers can you give. then do 4^5 for your answer.this would be something like the first question could be a and the 2nd c or first b next c etc. if you can, ask the teacher for a better confirmation of what it's asking. if i'm assuming correctly what it's asking, it's 625 different variations.