Stability of Autoregressive Models

Consider the autoregressive model expressed as follows:

$Y_t = \phi Y_{t-1} + \epsilon_t$

In this model, $Y_t$ represents the current value of the time series, $Y_{t-1}$ is the previous value of the series, $\phi$ is the autoregressive coefficient, and $\epsilon_t$ is a white noise error term.

Which of the following statements is true regarding the stability of this autoregressive model?