Answer:The function that represents an exponential function is the 4th graph and it can be modeled as y = aeᵇˣ.What are exponential functions?The exponential functions are written in the form of y = aeᵇˣ, where the output y increases exponentially for the input x.In order to find the graph that represents an exponential function, we will discuss each of the following graphs,For the 1st graph, (Black),In the first graph, the graph is of a parabola, and the function which represents this kind of graph is a quadratic equation, therefore, this graph represents a parabolic equation. It is given by the function,y=ax²+bx+c or y=a(x-h)²+kFor the 2nd graph, (Red),In the second graph, the graph represented is the graph of a reciprocal function, the function that can be represented by the graph,y=a/x + bFor the 3rd graph, (Blue),In the third graph, the graph represented is the graph of root function, it can be modeled as,y = a+√(x+b)For the 4th graph, (Green),In the fourth graph, the graph represented is the graph of an exponential function, and it can be modeled as,y = aeᵇˣHence, the function that represents an exponential function is the 4th graph and it can be modeled as y = aeᵇˣ.Step-by-step explanation: