Answer:Answer: The correct procedure is "The type of salt and the amount of water are controls, and the amount of salt and the density are variables".
Step-by-step explanation:
In the given problem, Sheila conducts an investigation to see how the amount of salt dissolved in water affects the density of the water.
Density measures how much mass in a given volume.
When the salt is dissolved in a water then the density of water increases.
The density is affected by the salinity and the temperature. Salinity describes how much salt is dissolved in water. When the salt is dissolved in the cold water then it becomes denser than the warm water without dissolved salt.
Therefore, the correct statement is "The type of salt and the amount of water are controls, and the amount of salt and the density are variables".