D. Strong ....................
1. 15,000 years ago the humans were still hunter-gatherers. Their daily lives were largely based around one thing, finding enough food to survive through the next few days. This means that they had to constantly be on the move, be it for hunting animals, or for finding rich places with eatable plants. There was lot of walking, running, and scouting involved every day. It was a lifestyle of ''living through the day''.
2. During this period of time, the diet of the humans was consisted of animals they hunted, fish, and plants. There were differences from region to region though, so the people that lived along the coastline based their diet on marine animals, the ones that were living in colder regions were eating mostly meat, while the ones living in forested areas or grasslands had combination of plants and meat. The lifestyle in general was moving from place to place, be it on a daily basis, weakly, or seasonally, depending on the conditions. Some of these people were making small shelters, some of which were retractable and they were moving them with them, while others were using caves.
3. There are many difference between the forager peoples and the agriculturalists. The foragers were nomads, thus they were moving very often from one place to another, while the agriculturalists were having a settled lifestyle. The nomads very often had bad injuries which were often fatal, usually because of hunting, while the agriculturalists had much better health because they had much safer lifestyle. The foragers were not able to produce their own food, but instead they were relying on mother nature, while the agriculturalists were producing their own food and had the food problem solved.
The answer is natural killer cells.
Natural killer cells are a type of lymphocytes and they are important for the innate immune system. They recognise stressed cells much faster than other immune cells. Their response is rapid and usually only a few days after a viral infection. They also respond to <span>cancer cell </span>formation. While other immune cells can detect only those harmful cells that have specific markers on the surface of the cell membrane, natural killer cells can even detect those cells that miss markers for apoptosis.
Light can pass through a transparent object, but light cannot pass through an opaque object.
