Please choose the correct answer to the question: Rosaria discovered a type of structure she could not identify in a sample of pond water. Her teacher looked into her microscope and explained that they were zygotes produced by one of the protists in her sample. The zygotes belong to which protist?

Answer1: amoeba Answer2: euglena Answer3: paramecium Answer4: volvox

Answer format: answer1/answer2/answer3/answer4