Answer them all please!!

Digestive = large instestine

respiratory = lungs

circulatory red blood cell

neurons=nerves

Explanation:

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.