Answer: Antibiotic Resistant Mutation
Explanation: Not all of the bacteria die because there are individuals in the population that have an antibiotic resistant mutation, which causes them to be adapted to dealing with the antibiotic. There will be a large population of bacteria again because the ones with the mutation survive, reproduce, and pass the antibiotic resistance trait on.
Parietal cells produce gastric acid (hydrochloric acid) in response to histamine (via H2 receptors), acetylcholine (M3 receptors) and gastrin (gastrin receptors). Parietal cells contain an extensive secretory network (called canaliculi) from which the HCl is secreted by active transport into the stomach.