Consider the following expressions which indicate the step or impulse response of an initially relaxed control system:
1. \(\left(5-4 e^{-2 t}ight) u(t)\)
2. \(\left(e^{-2 t}+5ight) u(t)\)
3. \(\delta(t)+8 e^{-2 t} u(t)\)
4. \(\delta(t)+4 e^{-2 t} u(t)\)
Those which correspond to the step and impulse response of the same system include:
(a) 1 and 3
(b) 1 and 4
(c) 2 and 4
(d) none of these