Margo, who is in her early 20s, is about to marry. if current literature is correct, when might she expect the most stress and unhappiness in her marriage?

Which of the following  bestillustrates a negative reinforcer?               a.  copland gives up candy to stave off chronic acid indigestion.    b.  nancy learns that she prefers chocolate over vanilla.    c.  carmine changes his major to english lit after failing a math exam.    d.  on a hot day, lindberg always drinks lemonade.