You are conducting a study on the health of people who have been exposed to radiation and those who have not been exposed to radiation. which of these methods of obtaining data should you most likely adopt and why?

a. an observational study because it involves the pre-existing condition of the subjects
b. an experimental study because it will give the most accurate results
c. an experimental study because results can be obtained much faster using this technique
d. a sample survey with only people who were not exposed to radiation because it involves random selection
e. a sample survey with only people who were exposed to radiation because it involves random selection

Option A, An observational study because it involves the pre-existing condition of the subjects

Explanation:

In an observational study, a researcher's aim is to observe the effect of an unusual condition, medicine, treatment, or any other intervention on the subject of the experiment without differentiating whether the subject was ever exposed to any such condition or not. Also, this kind of study involves study of pre-exposure condition as well thus, it becomes easy to identify what are the impacts of any treatment/medicine/unusual condition.

Hence, option A is correct.

children tend to take more after their grandparents more than their parents. it’s the dna you received that was passed down to you somewhere in your family. maybe one of your grandparents had/has straight hair and you might have gotten it from them.

volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. these particles serve as nuclei for the formation of water droplets (hydrosphere). rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere).