C? the cardiovascular system transports nutrients, oxygen, and hormones to cells throughout the body but it also removes metabolic waste.
The actual answer is, "A", an ocean trench.
You can find out more about them by researching them up on Google, it's only a few phrases and a hit on the enter key :P
Answer:
<em><u>Individual organisms live together in an ecosystem and depend on one another. ... One category of interactions describes the different ways organisms obtain their food and energy. Some organisms can make their own food, and other organisms have to get their food by eating other organisms</u></em>
7 is neutral but the ones that would be considered acidic is B
