23.16 A cube has a total of $n$ axes of symmetry, then $n$ equals
(A) 3 .
(B) 4 .
(C) 9 .
(D) 13 .
(China Beijing High School Mathematics Competition, 1985)
[Solution] As shown in the figure, connecting the centers of opposite faces of the cube, there are three such lines, which are three axes of symmetry.

Connecting the midpoints of opposite edges on the opposite faces of the cube also forms axes of symmetry, totaling six.
In total, the cube has nine axes of symmetry.
Therefore, the answer is $(C)$.