Question: 2018 Fall Midterm - 1
Let $n \geq 3$ be an integer and let $S$ be a set consisting of $n$ elements. How many ordered
triples $(A, B, C)$ are there for which $A \subseteq S$, $B \subseteq S$, $C \subseteq S$, and $A$, $B$,
and $C$ are pairwise disjoint?
(a)
$4^n$
(b)
$3^n$
(c)
$5^n$
(d)
$2^n$