The <u>general</u> <u>expression</u> for the <u>exponential function</u> is where
Note that the graph of each exponential function passes through the point (0,a), because Since then options A and C are false.
First point in options B and D is (0,1), then
and you get the expression for the exponential function.
Points (0,1), (1,3), (2,9) and (3,27) represent the powers of 3. In this case
Points (0,1), (1,2), (2,5) and (3,10) couldn't generate any exponential function, because if then
Answer: correct choice is D