Explanation
Correct answer: D.
Choice D is correct. It's given that the expression represents the area, in square centimeters, of a rectangular cutting board, where is the width, in centimeters, of the cutting board. The area of a rectangle can be calculated by multiplying its length by its width. It follows that the length, in centimeters, of the cutting board is represented by the expression .
Desmos solution:
Note: Set a sample width, and evaluate the area. Dividing area by width gives w+9, confirming that is the length.
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect. This expression represents the area, in square centimeters, of the cutting board, not its length, in centimeters.
Choice B
Choice B is incorrect. This expression represents the width, in centimeters, of the cutting board, not its length.
Choice C
Choice C is incorrect. This is the difference between the length, in centimeters, and the width, in centimeters, of the cutting board, not its length, in centimeters.