\item \self In the following list, tick
    all items that conform to the Disjunctive Normal Form (DNF).

\begin{itemize}
  \item[$\square$] $(a \wedge b \wedge \neg c) \vee (\neg b
      \wedge \neg c) \vee (e \wedge \neg f)$
  \item[$\square$] $(a \vee b \vee \neg c) \wedge (\neg b
      \vee \neg c) \wedge (e \vee \neg f)$    
  \item[$\square$] $\neg b$
  \item[$\square$] $a \wedge \neg b$
  \item[$\square$] $a \vee \neg b$
  \item[$\square$] $a \vee (\neg b \wedge c)$
  \item[$\square$] $(a \vee \neg b) \wedge c$
  \item[$\square$] $\neg(p \vee q)$
  \item[$\square$] $x \vee \neg y \vee z$
\end{itemize}