When a primary tumor spread it called methastastasis
A) both have strong scientific support.
I think the answer is the individuals born per unit time.
Because good researchers rely on first hand account or better said primary evidence. The reason why they rely on primary evidence is because it is usually the most reliable. Much more so than secondary or even tertiary evidence. This enables them to understand the history of a certain topic better.
The answer is B) Chlorophyll