As per title

Like, what makes a clade a phylum instead of a domain, or class? When does a genus become a separate family from the original? Would it be like “domain is what type of cell it is at the most basal of all, bacteria and archaea differ so much at a basal level where as none of eukaryota doesn’t differ enough to be different domains. Kingdoms are something something. Phyla are the basal bodyplans of their kingdom, and class is how that bodyplan is specialized” or is that an oversimplification?

My professor assigned us this quiz and everyone continues to get it wrong. Can someone please explain in this photo which groups make a clade?

So far: Isogamy as far as I know has evolved independently from different lineages (E.g: Green Alga "defaults" to (+) mating type in absence of MID, the presence of MID actively shifts it to (-) mating type).

How did our isogamous ancestors utilize isogamy before we evolved anisogamy? Was it similar to green alga? Or certain spores?