Parasites need a host. If a host tries to get rid of the parasite or kill it, then the parasite either has to leave the body or die.
A scientist may look for patterns in the data to identify trends. This helps the scientist predict new outcomes.
D. a viral disease because it is known and unknown and spreads.
The carbon cycle maintains the balance between the organic remains and carbon dioxide. In this cycle the the incorporation of carbon dioxide inside the plants by photosynthesis occurs and it is returned to the atmosphere by the process of respiration as well as the decaying dead organisms.