Nucleus:
Unlike prokaryotic cells, eukaryotic cells have: A membrane-bound nucleus, a central cavity surrounded by membrane that houses the cell's genetic material. A number of membrane-bound organelles, compartments with specialized functions that float in the cytosol.
(Credits to Picture: Khan Academy)
Natural laws would be the answer to the question
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Answer:
The secondary source is the evidence of someone who was not present at the time of occurrence of the event e.g., books written by historians. The secondary source is also of great historical importance to the historians. Although secondary source is itself dependent on primary sources.
