Assuming the first and second derivatives of f and g exist, find a formula for (d²)/(dx²)[f(x)g(x)]. Select the correct answer below.
1) (d²)/(dx²)[f(x)g(x)] = f"g"
2) (d²)/(dx²)[f(x)g(x)] = f''g''
3) (d²)/(dx²)[f(x)g(x)] = f''g''
4) (d²)/(dx²)[f(x)g(x)] = f'g'