amoeba euglena paramecium volvox
I gave my students this multiple choice question: A scientist was observing a unicellular organism over a period of time. He noticed that vacuoles kept moving to the same place in the plasma membrane to empty their contents outside the cell. Which organism was he observing?

Only one answer is correct among these 4 choices:
- amoeba
- euglena
- paramecium
- volvox

Could you tell me which one is correct?

paramecium