A、Our self-respect. B、Our financial rewards. C、Our advertising ability. D、Our friendly relationship. A短文一开始引出话题：快乐的生活；接着说话者用一个事例

Do you want to live with a strong sense of peacefulness, happiness, goodness, and self-respect? The collection of happiness actions broadly categorised as "honor" help you create this life of good feelings.
    Here’s an example to show how honorable actions create happiness.
    Say a store clerk fails to charge us for an item. If we keep silent, and profit from the clerk’s mistake, we would drive home with a sense of sneaky excitement. Later we might tell our family or friends about our good fortune. On the other hand, if we tell the clerk about the uncharged item, the clerk would be grateful and thank us for our honesty. We would leave the store with a quiet sense of honor that we might never share with another soul.
    Then, what is it to do with our sense of happiness?
    In the first case, where we don’t tell the clerk, a couple of things would happen. Deep down inside we would know ourselves as a type of thief. In the process, we would lose some peace of mind and self-respect. We would also demonstrate that we cannot be trusted, since we advertise our dishonor by telling our family and friends. We damage our own reputations by telling others. In contrast, bringing the error to the clerk’s attention causes different things to happen. Immediately the clerk knows us to be honorable. Upon leaving the store, we feel honorable and our self-respect is increased. Whenever we take honorable action we gain the deep internal rewards of goodness and a sense of nobility.
    There is a beautiful positive cycle that is created by living a life of honorable actions. Honorable thoughts lead to honorable actions. Honorable actions lead us to a happier existence. And it’s easy to think and act honorably when we’re happy. While the positive cycle can be difficult to start, once it’s started, it’s easy to continue. Keeping on doing good deeds brings us peace of mind, which is important for our happiness.
Questions 19 to 22 are based on the passage you have just heard.
19. What does the positive action in the example contribute to?
20. What does the speaker think about keeping silent about the uncharged item?
21. How will we feel if we let the clerk know her mistake?
22. Which can be the best title of this passage?