Final answer:
ELISA is the phenotypic method that uses antibodies to detect specific antigens in prokaryotes, unlike Gram staining, PCR, or antibiotic sensitivity testing.
Step-by-step explanation:
To identify prokaryotes by analyzing antibody reactivity, the appropriate phenotypic method is the Enzyme-Linked Immunosorbent Assay (ELISA). This method utilizes antibodies to detect the presence of specific antigens related to the prokaryotes being studied. It's different from methods like Gram staining, which is used for determining the Gram reaction of bacteria and provides information on cellular morphology, or Polymerase Chain Reaction (PCR) and electrophoresis, which are genetic methods used to amplify and analyze DNA sequences. Antibiotic sensitivity testing is used to determine the susceptibility of bacteria to various antibiotics, not for detection based on antibody reactivity.
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