This QOD actually has 2 answers that are correct, and should reflect such.

The "IN" statement can be used as both a predicate and an operator. See BOL:

Logical Operator

IN - TRUE if the operand is equal to one of a list of expressions.

Predicate:

Is an expression that evaluates to TRUE, FALSE, or UNKNOWN. Predicates are used in the search condition of WHERE clauses and HAVING clauses, the join conditions of FROM clauses, and other constructs where a Boolean value is required.

Thus, with the answers set up the way that they are, with only one answer being selectable, we should get credit for either answer being correct.