In the following valid domaincalculus query, what does "exists SSN$"$ refer to$?$

$1$ pts

drc$6$:$=\{$LNAMEFNAME I

$($exists SSN$)($employee$($FNAME$,$

$,.$LNAME, SSN$,-$s$-$s$-$s$-$s$-$s$-)$ and

not $($dependent $($SSN$,$

$$ any one row of employee

$$ all values for the variable SSN

O any one value for the variable SSN