Answer:
Number of bacteria required 
Explanation:
Given -
Size of each bacterium
micrometers long
These bacteria are arranged end to end.
The size of chain to be formed is equal to
centimetres
Let us say that in forming a chain of
centimetres nearly X number of individual bacterium are required.
hence, number of bacterium required to form
centimetres chain can be represented as

Number of bacteria required 
1) appearance of beard and moustache
2) broadening of chest and shoulders
3) changing of voice into a more grave one
The answer is C, because it was done on purpose, therefore NOT naturally. Not done by nature.
<span>Helium nuclei have a positive charge of 2+ when observed. Compared to a hydrogen nuclei, we can see that the Helium nuclei is more difficult to fuse as it has a greater charge than Hydrogen 1+. This chemical difference makes the answer true.</span>