The organelle which eliminates water from the body of a protozoan is the

Step 1: Analyze the question The question asks which organelle removes excess water from a protozoan (e.g., Amoeba or Paramecium).

Step 2: Explain the concept Protozoans live mostly in freshwater, which is hypotonic to their cytoplasm (it has a higher water concentration than the cell's contents). Water therefore keeps entering the cell by osmosis. If nothing removed it, the cell would swell and burst.

To prevent this, protozoans have a contractile vacuole. It:

• collects excess water from the cytoplasm,
• swells as it fills,
• then contracts and expels the water out of the cell.

This process is called osmoregulation. It also removes some dissolved waste.

Step 3: Check each option

• A. Plasma membrane: It controls what enters and leaves the cell, but it does not actively collect and expel water.
• B. Contractile vacuole: Correct. It is the specialized organelle for pumping out excess water.
• C. Nucleus: It controls cell activities and holds the genetic material. It has no role in water removal.
• D. Cell wall: Protozoans do not have a cell wall. Cell walls are found in plants, fungi, and bacteria.

Step 4: Answer The correct option is B. contractile vacuole.

Tip: Remember the name. A vacuole that contracts pushes water out. Whenever you see "protozoan" together with "osmoregulation" or "removing excess water," think contractile vacuole.