Redundancy questions deal with wordiness.
Remember that the correct answers to many grammar questions are quite short. Ask yourself: is all the information in the sentence necessary, or is it repetitive?
Incorrect:
"The dramatic movie filled with drama caused people to cry."
If it's a dramatic movie, we already know that it's "filled with drama."
Correct:
"The dramatic movie caused people to cry."
It is often not necessary to mention the definition of the opposite of a concept in a sentence.
"The private golf club, which is not public, is very well maintained."
If we know the club is private, we don't have to mention that it's not public.
"The private golf club is very well maintained."
