Pollution in our waterways is a major health concern. Researchers are sampling fish in a freshwater lake for signs of health problems and noting their weight and health status indicators. Which if the following statements is true regarding this study? This is an observational study because researchers did not purposely expose the fish to pollutants. This is not an observational study because researchers had to sample fish and couldn't just watch them in the water. This is an observational study because the researchers measured variables. This is an observational study because researchers observed health status indicators in the sampled fish