It may be c, if not you can punch me in the face.
Passive transport is a naturally occurring phenomenon and does not require the cell to expend energy to accomplish the movement. In passive transport, substances move from an area of higher concentration to an area of lower concentration in a process called diffusion.
The answer is immune system
The Earth is around 4.6 billion years old. Earth has a slightly squashed sphere, measuring 7,973 miles (12,756 km) in the diameter at the equator.
