D. you are not making any motion
Dumping waste is different from dilution and dispersion. Dumping waste is directly disposing your waste and not regulating its effect to the environment. Dilution is done usually before waste water disposal, meaning adding water to the waste to minimize its concentration.
Answer:
Save the *minerals* used to extract metals.
In descriptive investigations, we still haven't formed any hypothesis yet so we seek information by asking question.
It's not repeatable because repeating the questions over and over again without any clue about what we want to seek is completely waste of time.
Hope this helps xox :)