In terms of being a tool of public health policy, the study of epidemic diseases has an advantage over the effects of toxins on animals: in epidemiology, there is no need to make inferences between different kinds of organisms. Which of the following options can be inferred from the above? ['In epidemiology, inferences between organisms are just auxiliary tools.', 'Epidemiology is a precise science.', 'In epidemiology, humans can be directly the subject of research.', 'Toxin studies in animals draw conclusions slower than epidemiology.']