Answer: Option (D) is the correct answer.
Step-by-step explanation:
A saturated solution is defined as the solution which contains maximum amount of solute into the solvent.
And, on adding more amount of solute it will not be able to dissolve into the solvent. This shows that saturation point has reached and the solution is saturated.
So, at this point the excess of solute which is not able to dissolve will settle down at the bottom.
Thus, we can conclude that the statement when additional sodium nitrate is added, it all settles to the bottom of the container is the best evidence that the solution is saturated.