The answer is E. Honest.
Courteous, humble, civil, and polite are all words that describe someone who is respectful and considerate of others. Honesty, on the other hand, is a quality of being truthful and fair. While it is possible to be all of the above and also be honest, it is also possible to be courteous, humble, civil, and polite without being honest. For example, someone might be courteous and polite to their boss in order to get ahead at work, even if they don’t respect them or think they are a good person. Or, someone might be humble and modest about their accomplishments in order to make others feel better about themselves, even if they are actually very proud of what they have achieved.
Honesty is a more fundamental quality than the others, and it is essential for building trust and relationships. Without honesty, it is difficult to have meaningful interactions with others.