8. þ C. The equality operator requires a single-row subquery, and the
conditional subquery could return several rows.
ý A, B, and D. A is incorrect because the statement will fail in all
circumstances except the unlikely case where there is zero or one employee.
B is incorrect because this is not a problem; there need be no relationship
between the source of data for the inner and outer queries. D is incorrect
because the subquery will only run once; it is not a correlated subquery.
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