The answer to your question is A
Independent: The second group is not given the drug.
Dependent: Dr. Smith wants to examine weather a new drug increases the maze running performance of older rats.
Constants: Dr. Smith teaches two groups of older rats to find a piece of tasty rat chow in the maze.
Answer:
Transparency of water relates to the depth that light will penetrate water. The change that occurs is from predominantly yellow light at the surface to blue-green at depth in clear water or yellow-green in waters having a high concentration of dissolved organic material.
The Golgi apparatus deals with packing of the cell!