The excerpt that shows the condescending attitude of upper-class characters in Pride and Prejudice is number 3.
Numbers 1 and 2 focus more on how the lower-classes tend to regard the upper-class and what their social behavior is like. Let us not forget that Mr. Bennet was considered a gentleman since he did not need to work and was able to live off an inheritance. However, he was still far from belonging among the richest.
Number 4 does describe a condescending attitude on Mr. Darcy's part, but not for his being wealthy. This excerpt shows how opposite his own and Mr. Bingley's personalities - his best friend - are.
Now, excerpt number 3 describes Mr. Bingley's sisters who, unlike his brother, took their rank and money very seriously and chose to despise the less fortunate. They thought so highly of themselves that they were able to forget that someone in the family - even if it was a long time ago - had to actually work to make the fortune they inherited. They believed they "were therefore in every respect entitled to think well of themselves, and meanly of others." That behavior is shown in the narrative by other upper-class characters as well, such as Mr. Darcy's aunt, whose words were always impertinent but never contested, since no one - except maybe for Elizabeth, the main character - would have the courage to do so.
