The impulse response of an LTI system is $h(t)=\delta(t)+0.5 \delta(t-4)$, where $\delta(t)$ is the continuous-time unit impulse signal. If the input signal $x(t)=\cos \left(\frac{7 \pi}{4} t\right)$, the output is______________.
- $0.5 \cos \left(\frac{7 \pi}{4} t\right)$
- $1.5 \cos \left(\frac{7 \pi}{4} t\right)$
- $0.5 \sin \left(\frac{7 \pi}{4} t\right)$
- $1.5 \sin \left(\frac{7 \pi}{4} t\right)$