9. (10 points) This figure is made up of at least ( ) unit cubes neatly stacked.
A. 12
B. 13
C. 14
D. 15
【Answer】Solution: Observe that if the top view is the following shape (the number on the small square represents the number of cubes stacked above), the minimum number of cubes is placed.
So the minimum number of cubes placed is $1+2+2+4+1+2+1=13$, hence the answer is: B.