researchers compare the body composition of cattle feeding on a grain diet with that of cattle feeding on a…

researchers compare the body composition of cattle feeding on a grain diet with that of cattle feeding on a grass diet. this method of gathering data is classified as a census. a sample survey. an experiment. an observational study.
Answer
Answer:
D. an observational study.
Brief Explanations:
Researchers are just observing cattle on different diets without interfering or manipulating variables, which is characteristic of an observational study.