This cannot be answered without the table. If each snowfall value is different for each elevation, then it does represent a function. That is, if I have 2000ft (4inches), 4000ft (5 inches), 5000ft (6inches). This represents a function because each Y-value (inches) is unique. If I have 2000ft (4 inches), 4000ft (5 inches), 5000ft (4 inches), this does NOT represent a function because "4 inches" is duplicated.
Assuming this is the same as the other question I just answered and all of the snowfall inches are unique then the answer is C.