Answer:
Contractile vacuole.
Step-by-step explanation:
Cell consists of various cell organelle that plays an important role in the cell metabolism. The membrane bound cell organelle are absent in case of prokaryotes.
The plant cells and paramecium although shares similar cell organelle but they still shows many differences. Contractile vacuole, cell organelle is present in paramecium as it helps the organisms to lose and gain the water and also maintains the cell osmolarity. Contractile vacuole is absent in plant cells.
Thus, the correct answer is option (D).