Answer:
Part A: {(0,9),(1,8.5),(2,8),(3,7.5),(4,7),(5,6.5)}
Part B: This relation is a function, because each x input has it's own y output.
Part C: Yes, the relation would still be a function as the y-coordinate is not repeating itself for different x-coordinates. Decreasing the number of this rate of change does not affect whether the relation is a function or not.
Good luck on your test! I hope I helped :)