Answer:
The scientist tested one variable to determine what caused the number of leaves to change.
Explanation:
Answer:
These vents contribute dissolved minerals to the oceans, which is one reason the oceans are salty. Rivers and surface runoff are not the only source of dissolved salts. Hydrothermal vents are recently-discovered features on the crest of oceanic ridges that contribute dissolved minerals to the oceans.
We as human beings can change our transportation, eating habits and our home energy use.