Looking for short strategy based solution

A ladder is leaning against a wall in a slanted position. The distance between the top of the ladder and the ground is 5 ft, and the wall and the ground form a 90° angle.
The ladder then slips:
The top of the ladder moves downward by |x| ft along the wall.
The bottom of the ladder moves away from the wall by |y| ft along the ground.

Quantity A: |x|
Quantity B: |y|

I can think of a algebraic based proof for possible choice D, but solving using proof may not be optimal in exam. So, I’m looking for some strategy based solution or intution based solution that would help me get this question quickly.

Put a pencil in that position against a wall, point facing up.

Slowly move the eraser an inch away from the wall. What is the tip doing?