Final answer:
The lines AB and CO are perpendicular because their slopes are negative reciprocals: 5/4 and -4/5. Two lines are perpendicular if one has a positive slope and the other has a negative slope that is its reciprocal.
Step-by-step explanation:
The question pertains to the properties of perpendicular lines in the context of slope in a Cartesian coordinate system. The slopes of two perpendicular lines are negative reciprocals of one another. Considering the slopes mentioned, if the slope of line AB is 5/4 and that of line CO is -4/5, then these slopes are negative reciprocals. Hence, these lines are perpendicular to each other, as one has a positive slope and the other has a corresponding negative slope.
If the slope of line AB was 5/4 and the slope of CO was -3/2, then they would not be perpendicular because the slopes are not negative reciprocals of one another. Therefore, the correct response is 'a) Yes, because the slope of AB is 5/4 and the slope of CO is -4/5', which indicates that line AB is perpendicular to line CO.