The Laplace transform of the continuous-time signal $x(t)=e^{-3 t} u(t-5)$ is_____________, where $u(t)$ denotes the continuous-time unit step signal.
- $\frac{e^{-5 s}}{s+3}, \operatorname{Real}\{s\}>-3$
- $\frac{e^{-5(s-3)}}{s-3}, \operatorname{Real}\{s\}>3$
- $\frac{e^{-5(s+3)}}{s+3}, \operatorname{Real}\{s\}>-3$
- $\frac{e^{-5(s-3)}}{s+3}, \operatorname{Real}\{s\}>-3$