To paraphrase is to reword information so that it still says what was said but in a whole different way through your own words.
Example, you go on this really trustworthy website and you plan on just copying and pasting but which is not allowed, that would be plagiarism... Don't plagiarize, instead read the information and take out the main points and reword it.
The correct way to punctuate is seen in b:
<span>To whom it may concern:
</span>
In formal settings and when you don't know the exact identity of the person a dresses it is usual to use a colon in this situation.
Answer:
the authors purpose is to convey the idea of learning
