dr. landen is performing an experiment to determine if a new chemical that he has synthesized is effective at killing plated colonies of group a streptococcus bacteria, which can cause infections in humans and other organisms.

dr. landen plates the same amount of group a streptococcus onto seven identical plates, then places differing amounts of his newly synthesized chemical onto the plates. he keeps the plates in identical environments, then measures the amount of bacteria present after 24 hours.

dr. landen's results show that the chemical is very effective at killing the plated bacteria. what could dr. landen hypothesize next in order to continue his research?