If $|A| = 3$ and $|B| = 4$, the number of elements in $A \times B$ is:
A$3$, equal to the cardinality of $A$ alone
B$4$, equal to the cardinality of $B$ alone here
C$12$, since $|A \times B| = |A|\cdot|B|$
D$7$, equal to the simple sum of cardinalities
Answer & Solution
Correct answer: C. $12$, since $|A \times B| = |A|\cdot|B|$
$|A \times B| = |A|\cdot |B| = 3\cdot 4 = 12$.
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