A scientist found a correlation between the oxygen level ina pond and the water temperature. As the watertemperature increased, the oxygen level decreased.To find out whether the change in the water temperature caused the oxygenlevel to change, what could the scientist do?A. Measure water temperature at various depths in the pond to findout whether it changes.B. Perform a controlled experiment by increasing and decreasingwater temperature and measuring changes in oxygen levels.C. Add more oxygen to the water and take measurements todetermine whether the temperature changes.OD. Compare oxygen levels with carbon dioxide levels in water atvarious temperatures.