Question

If $A=\{a,b,c,d\}$ and $B=\{a,b,c\}$, then $A-B=$_____.

• A. {a-a,b-b,c-c,d}
• B. $\varphi$
• C. {d}
• D. None of the above

Answer 1

The correct option is C {d}

For any two sets $A$ and $B$, the difference set :$A-B$ is the set of all those elements of $A$ which are not present in $B$.
Thus, for $A=\{a,b,c,d\}$ and $B=\{a,b,c\}$,
$A-B=\left\{d\right\}$