Mark raises guppies in an aquarium. He finds out that guppies reproduce very rapidly, and the number quadruples every month. He starts out with only 2 guppies, and the function y equals 2 times 4 to the x models the number of guppies he will have after x months. Which graph represents this function?

The graph of the function that models the reproduction of the guppies in the aquarium is of the exponent form, where its base is 4 and X is the exponent.
 The domain of this function is the set of all real numbers and the range are all positive reals.
 The function is close to zero for negative values of X, but for positive values it grows rapidly.
 Below is a graph of the aforementioned function:
 y = 2 * (4 ^ x)
 For x between -1.5 and 0.5 and for x between -6.5 and 5.5