ASAP Which of the samples seen are the earliest versions of possible photosynthesizers? How do we hypothesize this?

Question

Which of the samples seen are the earliest versions of possible photosynthesizers? How do we hypothesize this?

Given Cell Slides (under a microscope)

1) Corn (Zea mays) Root

2) Pivot (ligustrum Leaf)

3) Lilac Leaf

4)Lilium Young

5)Anthoceros sporophyte

6)Zea Mays leaf

7)Corn Zea May

8)Blue-Green Algae Mix

9) Volvox

Answer 1

Blue-green algae would be the earliest photosynthesizer on the list. Since it is the only unicellular organism, let alone a prokaryote, this indicates that the organism is much older than the rest.