A proportional relationship on a graph is characterized by a straight line that passes through the origin (0,0).
Based on the description:
- Curve A is a straight line that does not pass through the origin.
- Curve B is a straight line that also passes through the origin, indicating a proportional relationship.
- Curve C is not linear and does not represent a proportional relationship.
- Curve D is a straight line but does not pass through the origin.
Thus, the correct answer is:
B