To determine which two organisms are most closely related based on evolutionary relationships, we would need to see the phylogenetic tree or the classification illustration you mentioned. However, a common way to assess closeness in relationships is to see which organisms share a more recent common ancestor.
Without seeing the specific diagram, I can't directly answer which pair of organisms (A and G, C and F, B and G, or E and F) are most closely related. However, typically, the organisms that branch off closest together on the tree are considered more closely related than those that have a larger divergence.
If you can describe the branching pattern or relationships shown in the illustration, I would be happy to help analyze it further!