Pollution, Global Warming, deforestation, Mass extinction
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.
A) Landfills have to do with trash and fossil fuels are not trash.
Sedimentary rocks are 'built up' over time, and if something dies overtime, lets say an animal, it will get buried and minerals will fill it and it becomes a fossil. fossils are important because they tell us about the past and what is was like way back when.
