Which of these factors should be compared to best determine how closely species are related to each other?

Physical similarities in body structures should be compared to best determine how closely species are related to each other. Classification involves the grouping of organisms based on their similarities, therefore, organisms with similar characteristics in the body structures are grouped into one taxon. Linnaeus designed a system to classify organism based on similarities in body structures and physical form. Taxonomy was developed as part of science that focuses on naming and classifying or grouping organisms according to their similarities.