Solution (source code)

= Solution

For any commutative ring with identity, the <maximal ideal quotient criterion> states that an ideal $I$ is maximal exactly when $R/I$ is a field. Applying it to $I=(p)$ proves
$$
\boxed{(p)\text{ maximal}\quad\Longleftrightarrow\quad R/(p)\text{ is a field}.}
$$