Which of the following is the differential equation whose solution is \[y = { a }^{ x } \]

y' + (log a)y = 0 y' - (log a) y =0 (log a) y' + y = 0 (log a) y' -y = 0

y' - (log a) y =0

y' = \( { a }^{ x } (log a )\)