Which graphs below represent an exponential function? select all that apply.

The two graphs in the second picture are the graphs of exponential functions. You can detect it from the L shaped graphs. 

The very first graph represents a linear function. A straight line always represents a linear function. In a Linear function, the change in the values of y is constant throughout in relative to change in x values.

The final graph represents a quadratic function rising on both ends. 

Therefore, option b and c are the correct answers