Answer: Graphs B and C are functions.
Explanation:
For a graph to be classified as a function, there needs to be one y value for every x value. In other words, an x value can't have two values in a function.
To easily test this, we can use something called the vertical line test. Draw a straight vertical line right through the middle of the graph. If the vertical line intersects the graph more than one time, then it is not a function. If we do this to the four curves here, graphs B and C pass the vertical line test whilst graphs A and D fail it making graphs B and C functions!
Hope this helps!!