- A zygote is formed immediately after fertilization
- Fertilization is a stage in the sexual reproduction process
- Therefore, if a zygote is formed then a sexual reproduction process has happened

- If a zygote is formed then a sexual reproduction process has happened
- A student observes the formation of zygotes by one of the protists
- So, a sexual reproduction process has happened in the protists that the student observed

- Volvox is a kind of protist
- Volvox reproduces sexually
- So, volvox is a kind of protist that reproduces sexually

- A sexual reproduction process has happened in the protists that the student observed
- Volvox is a kind of protist that reproduces sexually
- So, the protist may be volvox

Therefore, the protist may be volvox
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?

Context
- A student observes the formation of zygotes by one of the protists 
- A zygote is formed immediately after fertilization 
- Volvox is a kind of protist 
- Fertilization is a stage in the sexual reproduction process 
- Volvox reproduces sexually