\item \self Tick each correct ending of the following sentence. "A
    \emph{Conjunctive Normal Form} is \dots
    \begin{itemize}
        \item[$\square$] \dots a conjunction of disjunctions
            of literals."
        \item[$\square$] \dots a conjunction of clauses."
        \item[$\square$] \dots a formula that consists only
            of logical AND operations on sub-formulas which
            only consist of OR operations on just variables
            and negations of variables."
    \end{itemize}