The figure shows three squares. From the given that QM = 2 &times; ON, we can find all side lengths.<br><br>&bull; ON is the side of the smallest square = 3 cm (from the previous part).<br>&bull; QM = 2 &times; 3 = 6 cm (largest span).<br>&bull; KN spans the full length of all three squares combined.<br>&bull; From the figure, adding the labelled sides: the three squares have sides that sum to KN.<br>&bull; KN = 23 cm (as determined from the figure dimensions).<br><br>Final Answer: C: 23 cm