What happens to the relationship between two quantities in a direct proportion?

In a direct proportion, the relationship between two quantities is such that when one quantity increases, the other quantity increases at a consistent rate, and conversely, when one decreases, the other also decreases consistently. This consistent increase or decrease reflects the inherent nature of direct proportionality, where the ratio between the two quantities remains constant.

For example, if two quantities, say (x) and (y), are directly proportional, this can be expressed as (y = kx), where (k) is a constant. If (x) doubles, (y) also doubles, maintaining the same ratio. This predictability and reliability in how one variable changes in response to the other is central to understanding direct proportions.

Other options suggest varying relationships that do not align with the definition of direct proportion. Thus, the steady and predictable nature of the relationship characterized by a consistent increase or decrease is what makes the answer valid.