Answer:
Both the balloon and the object are positive
The answer is D, white blood cells.
The main function of white blood cells is to defense the body from bacteria or other pathogens. There's 2 main kinds of white blood cells, lymphocytes and phagocytes. Lymphocytes mainly produce antibodies that can kill bacteria or any pathogens, and phagocytes can ingest the pathogens directly.
Therefore, since the white blood cells can protect our body, they're part of our immune system.
North America and Europe lie entirely north of the equator. Almost all of Asia, most of Africa, and a part of South America are above the equator. Not sure if South America counts as 'mostly' though. That's up to you.
If a particular job of a cell was to swim a long distance to an egg with a flagella, then it would need more mitochondria. As mitochondria undergo cellular respiration and essentially utilize the carbohydrates for that particular cell to produce the final product of ATP high energy containing molecules needed for the movement.