Started at 0, the AR(1) has mean $\mu\frac{1-\phi^t}{1-\phi}$ and variance $\frac{1-\phi^{2t}}{1-\phi^2}$

Let $X_t=\mu+\phi X_{t-1}+Z_t$ where $Z_t\sim$ iid Normal $(0,1)$, the process started at time 0 with $X_0=0$. Which statements are correct? (i) $X_t=\frac{1-\phi^t}{1-\phi}\mu+\sum_{j=1}^t\phi^{t-j}Z_j$; (ii) $E(X_t)=\mu$; (iii) $V(X_t)=\frac1{1-\phi^2}$.