which best describes why American Indian groups were vulnerable to European diseases. They lacked the necessary vaccinations. They were unfamiliar with all diseases. They failed to take preventative measures. They lacked immunity to these diseases.

d is the correct answer.

b is incorrect because it makes food by itself

c is incorrect because us humans don't know how to produce their own food using the sun like plants.

a is incorrect because consumers can depend on carnivores for eating food for consumers to eat the dead organism. same thing with omnivores.