How many rectangles can be formed by the vertices of a cube? (Note: square is also a special rectangle).

A. $6$ B. $8$ C. $12$ D. $18$ E. $16$
1. **Identify the number of square faces in the cube:**
   A cube has 6 faces, and each face is a square. Therefore, there are 6 square faces.

2. **Identify the number of rectangles that bisect the cube:**
   These rectangles are formed by selecting two opposite edges on one face and two opposite edges on the opposite face. Each of these rectangles includes two face diagonals. There are 6 such rectangles, one for each pair of opposite faces.

3. **Count the total number of rectangles:**
   - Number of square faces: 6
   - Number of bisecting rectangles: 6

   Therefore, the total number of rectangles is:
   \[
   6 + 6 = 12
   \]

Conclusion:
The total number of rectangles that can be formed by the vertices of a cube is $\boxed{12}$.