I believe the answer is B, the survival of the fittest due to competition for resources. Survival of the fittest is a term that originated from Darwinian evolutionary theory was a way of describing the mechanism of natural selection. The biological concept of fitness is defined as reproductive success. Many organism overproduce to increase chances of survival for their organisms due to competition.
The correct answer is A. Spontaneous generation does not happen.
He wanted to show that cells always come from other cells, meaning that cells and life organisms cannot come from non-matter or dead matter. Meaning that maggots in rotting bodies are not made from the bodies.
Blood clots form when platelets and plasma proteins thicken to form a sort of solid mass. They can form from an injury, blood flowing slowly through your system, or even for no obvious reason.