What is meant by the statement cleaner than coal?

Which of the follow describes a disadvantage secondary sources have compared to primary sources?

Recently, crops of vegetables such as lettuce and green onions have been contaminated, while they are still on the farm, with bacteria that cause food poisoning. how will science influence the way the government responds to prevent an increase in food-borne diseases? because science has shown that lettuce and green onions are not nutritionally valuable, the government may pass laws that ban the sale of lettuce and green onions. because science has shown that there is no way to prevent bacterial contamination, the government may pass laws that punish businesses that buy lettuce and green onions. because science has shown that the washing of hands prevent the spread of infectious diseases among people, the government may pass laws that require hand washing by everyone who handles food. because science has shown there are ways to find the source of the contamination, the government may pass laws that require farm practices that reduce the contamination of lettuce and green onions.

1. -define adaptation2 explain darwin's theories of descent with modification and natural selection in detail3. -explain how each of these provides evidence for evolution: a. -fossil record, including superposition and transitional fossilsb-anatomy, including homologous structuresc-biological molecules, including dna and proteins4. -explain the difference between convergent and divergent evolution.5. -define and give three examples of artificial selection6. -define and give one example of coevolution.7. -explain biodiversity and how it benefits humans.8. -explain a type of population lest affected by environmental change.