The answer is probably B because white blood cells are part of the immune system, so help to fight diseases. The circulatory system helps to move the white blood cell around the body. Also, pathogens are disease causing organisms, and as you can see, they all relate very well. Hope i helped, have a nice day.
At the end of the result concludes RNA (Copied exact genes off of DNA)
The purpose of an experiment is to compare results with others.
The motion of the ball is mechanical energy
