Answer:
It is important to have more than one piece of evidence to make sure that the evidence is actually evidence. Or in other words, that the evidence is proven true. With only one piece of evidence, you can't be fully sure if calculations were correct, if the source was trustworthy, etc.
Multiple evidence is kinda like double checking math problems. If you don't do it, you can't be 100% certain the answer is correct.
A. Neutral water
Less than 7 is acidic (which has 6 letters, 6< 7)
More than 7 is alkaline (which has more than 7 letters). Alkaline = basic
7 is neutral
To preserve and keep them fresh
Explanation:
The traits more sensitive noses is advantageous to the species
not sure if this is what you need.