The correct answer is: Only conclusion II follows.
The first statement, “Some dreams are nights,” can be expressed in propositional logic as $p \land q$, where $p$ stands for “dream” and $q$ stands for “night.” The second statement, “Some nights are days,” can be expressed as $q \land r$, where $r$ stands for “day.”
The first conclusion, “All days are either nights or dreams,” can be expressed as $\forall x(r \lor p)$. This conclusion does not follow from the premises, because it is possible for there to be days that are neither nights nor dreams. For example, a day that is spent working or doing other activities that are not associated with sleep or dreaming would be a day that is neither a night nor a dream.
The second conclusion, “Some days are nights,” can be expressed as $\exists x(r \land q)$. This conclusion does follow from the premises, because the premises tell us that there are some nights that are also days. Therefore, there must also be some days that are nights.
In conclusion, only conclusion II follows.