Let $\left.\mid N_{1}(t), t \geq 0\right\}$ and $\left.\mid N_{2}(t), t \geq 0\right\}$ be independent renewal processes. Let $N(t)=N_{1}(t)+N_{2}(t)$
(a) Are the interarrival times of $\{N(t), t \geq 0\}$ independent?
(b) Are they identically distributed?
(c) Is $\{N(t), t \geq 0\}$ a renewal process?