Both facts and observations. If you are having trouble understanding this concept, follow up with your teacher, as it is very important. Hope this helps!
Answer:
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Natural selection is a theory developed by Charles Darwin. It is believed that animal species evolve by nature "selecting" the ones that are fit to live in specific environments. For example, if an animal lacks a trait that is needed for a certain environment, it is likely to die. The animals that have the needed traits are more likely to live and procreate, which will pass on the trait to its offspring. Hope this helped!
Answer:
(a) cell
Explanation:
"What do scientist call the basic unit of life?
The basic unit of life is the cell. In 1838, scientists Theodor Schwann and Matthias Schleiden came up with the original version of the cell theory, which concluded that the basic unit of living things is the cell."
