A researcher has hypothesized that the chemical tributyltin (an additive in boat paint) seeps out of the paint into the water and causes reproductive defects in developing marine snails. Which of the following would be a good control in an experiment that tests the effects of tributyltin on developing snails?A. Developing snails are kept in a dry tank to avoid exposure to contaminated water.B. Developing snails are kept in a tank of water and exposed to boat paint that does not contain tributyltinC. Developing snails are kept in a tank of water and exposed to below-expected levels of tributyltin.D. Developing snails are kept in a tank of water that has never been exposed to boat paint.