Mutualism because both animals benefit. The Elephant gets relived from the parasites that are on it and the bird gets food.
Cytoplasm maintains the internal pressure in the cell.
When testing a hypothesis, scientists use repeated trials and replication to make sure that they get the same answer each time, and that it isn't just a lucky guess the first time. They need be sure that the answer to their hypothesis is 100% the same every time.
