Answer:
Option B
Step-by-step explanation:
In order to prove that segment DE is not parallel to segment BC, Karen takes an indirect way, that is she assumes that DE is parallel to BC, then by using the basic proportionality theorem,
[tex]\frac{AD}{AB}=\frac{AE}{AC}[/tex]
Now, AD=6, AB=AD+DB=8, AE=7 and AC=10
therefore, [tex]\frac{6}{8}=\frac{7}{10}[/tex] according to basic proportionality theorem, but in actual, [tex]\frac{6}{8}{\neq}\frac{7}{10}[/tex].
Thus, DE is not parallel to BC, therefore Option B is correct.