Because its is a bit more rare than iron .
All they need for their living is carbondioxide in air ,water and some nutrients .so basically their roots are responsible for collection of water which contains life giving nutrients .but we take food as a solid substance which hasto be converted into energy
The last option is corrrect because when one species move away from an environment or die it lead to decrease in biodiversity as well as the overall health of ecosystem also decreases.
