Answer
____Brown Algae
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| _____ Red Algae
____|
_____ Green Algae
Basically, the fact that the DNA sequences are more similar in the red and green alga place them closer together on the phylogeny than either group to the brown algae.
Work Step by Step
Phlylogenies based on DNA sequences put organisms with more similar DNA closer together. Thus, with three groups, it is easy to see that two group together on the chart.