Given that the cell is round and incapable of producing its own food, the organelle you would assume the cell must have is:
A. plasma membrane
The plasma membrane is a fundamental structure found in all cells, regardless of their shape or ability to produce food. Chloroplasts are associated with photosynthesis (which produces food) and would not be present in a cell that cannot produce its own food. A cell wall is typical of plant cells and some prokaryotes but not all cells, especially animal cells. A central vacuole is more common in plant cells. Therefore, the only organelle that all types of cells, including round-shaped non-photosynthetic cells, must have is the plasma membrane.