Final Answer:
The best reason supporting the relationship between angle 2 and angle 4 is b) Corresponding Angles. Corresponding angles are congruent when lines are parallel, a key detail possibly overlooked in Marion's proof. Thus the correct option is b) Corresponding Angles.
Step-by-step explanation:
In the given scenario, the best reason supporting the relationship between angle 2 and angle 4 is that they are corresponding angles.
Corresponding angles occur when two parallel lines are intersected by a transversal. In this case, Marion might have overlooked this relationship when providing her proof.
Angle 2 and angle 4 are on the same side of the transversal and in corresponding positions with respect to the parallel lines. This means they are congruent if the lines are parallel. Marion may have omitted this crucial detail in her proof, overlooking the significance of corresponding angles in parallel line setups.
This relationship can be verified by the angles being congruent or equal in measure, a key element necessary to strengthen her proof. Thus the correct option is b) Corresponding Angles.