To find \( n(A \cup B) \), we use the formula for the union of two sets: \[ n(A \cup B) = n(A) + n(B) - n(A \cap B) \] Substitute the given values: \[ n(A \cup B) = 8 + 9 - 6 = 11 \]
The correct option is (C): \(11\)