What characterizes a direct relationship between two quantities?

A direct relationship between two quantities is characterized by the fact that as one quantity increases, the other also increases. This means that there is a consistent and proportional connection between the two, such that if you were to graph the relationship, you would see a straight line that slopes upward. This kind of relationship indicates that the two variables move in the same direction, demonstrating a positive correlation.

For example, if you consider the relationship between the distance traveled and the time taken at a constant speed, as time increases, the distance also increases, illustrating a direct relationship.

In contrast, the other options present different relationships: in the first scenario, both quantities might increase, but at different rates, which doesn't reflect a consistent direct relationship. The third option describes an inverse relationship where one quantity increases while the other decreases. The last option suggests that the quantities are always equal, which does not encompass the broader definition of a direct relationship, as it is more about proportional increases than a constant equality. Thus, the precise definition of a direct relationship is best captured by the option stating that as one quantity increases, the other also increases.