Supplementary angles are angles that add up to 180 degrees.
To find the supplementary angle to ∠EOD, we find the angle with ∠EOD that makes up a straight line.
Looking at the figure, EC is a straight line and both ∠EOD and ∠DOC fall on this line. These two angles make up 180 degrees.
Thus,
The one supplementary angle to ∠EOD is ∠DOC.
AnswerB