Final answer:
The function whose derivative is f'(x) = e^{5x} is given by option (a) 1/5e^{5x} + C.
Step-by-step explanation:
The function whose derivative is f'(x) = e^{5x} is given by option (b) e^{5x} + C.
To find the original function, we need to integrate f'(x) with respect to x. Integrate e^{5x} with respect to x to get:
f(x) = 1/5e^{5x} + C
where C is the constant of integration. Therefore, the answer is option
(a) 1/5e^{5x} + C