Hi! can anybody help me with this?

Does the table bellow represent a function?
Time, x (minutes): 0| 1| 2| 3|
-----------------------------
Water, y (Gallons):440| 428| 416| 404|
A.Yes
B. No

I'll get the answer myself, but i want to know how you can figure out that something represents a function. I'm having a bit of a hard time :(

What is your answer?

for any set of points, or for a graph, if for every value of x there is one and only one value of y, then the relation is a function.

You might want to google "vertical line test", there are a few nice clips that illustrate a simple visual way to tell if a relation is a function.