3. To determine how closely related organisms are.scientists consider all of the following EXCEPT embryonic structures. analogous structures. vestigial structures.

## Step 1<br />The question is asking which of the given options is not considered by scientists when determining the relatedness of organisms. The options are embryonic structures, analogous structures, and vestigial structures.<br /><br />## Step 2<br />Embryonic structures are considered by scientists because they can reveal similarities between different organisms, indicating a common ancestry.<br /><br />## Step 3<br />Vestigial structures are also considered by scientists because they are remnants of features that were functional in ancestral organisms but are no longer functional in the current organism. This can provide evidence of common ancestry.<br /><br />## Step 4<br />Analogous structures, however, are not considered by scientists when determining relatedness. This is because analogous structures are features in different species that perform the same function but have evolved separately, not from a common ancestor. They are a result of convergent evolution, where different species independently evolve similar traits as they adapt to similar environments or ecological niches.