The cells of parent algae have nuclei. Each offspring contains chloroplasts. Several offspring may be produced at once. Genetic material is contributed by two parent cells.
I gave my students this multiple choice question: Spirogyra are green algae that can reproduce sexually. Which of the following features identifies reproduction in Spirogyra as sexual reproduction?

Only one answer is correct among these 4 choices:
- The cells of parent algae have nuclei.
- Each offspring contains chloroplasts.
- Several offspring may be produced at once.
- Genetic material is contributed by two parent cells.

Could you tell me which one is correct?

Genetic material is contributed by two parent cells.