The fact about rectangles that we need to use is this:
Area of a rectangle = (length) times (width) .
If you tell us the area and give us only one dimension, we can easily find
the other one. We just divide the area by the dimension you give us.
You've given us just the area (112 cm²) and no other information.
ANY of the choices can be one dimension, and for each one,
we can calculate the other dimension.
-- If the width is 6 cm, then the length is 112 cm² / 6 cm = (18 and 2/3) cm
-- If the width is 8 cm, then the length is 112 cm² / 8 cm = 14 cm
-- If the width is 10 cm, then the length is 112 cm² / 10 cm = 11.2 cm
-- If the width is 12 cm, then the length is 112 cm² / 12 cm = (9 and 1/3) cm .