Step 1: Understand the geometry.
The truncated cone has a circular base (diameter 12) and is coaxial with the cube (10 × 10 × 10). When both are aligned on the same base, the cube cuts out a central cylindrical volume from the cone.
Step 2: What happens when cube vanishes?
The cube is removed along with the intersected portion of the cone. This means that instead of one full truncated cone, we are left with a truncated cone with a square hole passing through its middle.
Step 3: Compare options.
- (A): Shows cone split into small chunks, not correct.
- (B): Shows simple truncated cone (but cube effect missing). Wrong.
- (C): Shows cone with circular removal. Wrong (cube cuts square, not circle).
- (D): Shows truncated cone with four removed square-side cutouts – correct.
Final Answer:
\[
\boxed{\text{D}}
\]