Organisms that form index fossils

Which describes radioactive decay of a substance

Which of the following matches the organisms described with the correct domain? a. bacteria--unicellular, eukaryotic organisms with cell walls that do not contain peptidoglycanb. archaea--multicellular, eukaryotic organisms that do not have cell wallsc. eukarya--single-celled and multicellular organisms, with a defined nucleus and a variety of nutritional sourcesd. bacteria--unicellular, eukaryotic organisms that always lack cell walls

Cedric has a low fever and minor aches. yesterday, he went to the doctor for his booster shot and receive the flu shot. which best explains why he has this reaction?