Step 1: Understanding perspective.
In a correct perspective drawing, all objects must follow the vanishing points and recede correctly into space. The back wall window should show depth, meaning its inner edges must converge toward the same vanishing point as the room.
Step 2: Identifying the error.
- The side wall window is drawn in proper perspective, with its edges converging inward correctly.
- The table has legs and top receding consistently with the room's perspective.
- The walls are correctly drawn using linear perspective.
- The back wall window, however, is drawn completely flat — it shows no perspective depth, no inner sill, and no converging lines, making it inconsistent with the rest of the room.
Step 3: Conclusion.
Thus, the object that is NOT in perspective is (C) Window on the back wall.