a. Proportional Relationship 
b. Not a Proportional Relationship 
c. Not a Proportional Relationship 
1) Proportional relationships are graphically represented by Linear functions following this type: y=kx
2)  In a graphic the line of a Proportional relationship passes through the origin.
2.2) So examining the graphs, we can state that:
a. Proportional relationship For it passes on the origin (0,0)
b. Not a Proportional Relationship  Since it is not a straight line through the origin
c. Not a Proportional Relationship For it passes through the point (3,0)
3) Hence, the answer is