A

1003055705

Level: 
A
Given the sets \begin{gather*} A = \{1, 2, 3, 4, 5, 6, 7, 8, 9\},\\ B = \{3, 4, 5, 6, 7\},\\ C = \{6, 7, 8, 9, 10, 11, 12\}, \end{gather*} find the union \( A\cup B\cup C \).
\( \{1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12\} \)
\( \{1, 2, 3, 4, 5, 6, 7, 8, 9\} \)
\( \{6, 7\} \)
\( \{1, 2, 10, 11, 12\} \)