Only table D is a function. All of the others fail the "vertical line test." The definition of a function is for each input there is only one unique output. So for example, any given input value of x, there can only be one unique output value for y.
Amuffin recipe, which yields 12 muffins, calls for cup of milk for every 1 cups of flour. the same recipe calls for cup of coconut for every cup of chopped apple. to yield a batch of 30 muffins, how much flour will be needed in the mix?