Which sentence contains the main idea of the paragraph?

now you can stop feeling guilty about that bite of chocolate you had for dessert. chocolate has been found to be a cause of weight gain. but chocolate does have some health benefits. however, don’t reach for that chocolate cake just yet. researchers found that only people who had an average of one ounce of dark chocolate per day received the health benefit. dark chocolate is full of flavonoids, which can prevent diseases. flavonoids have been found to decrease cholesterol and reduce the blood clots that cause strokes. flavonoids also boost a natural chemical in your brain called serotonin. low serotonin can cause depression. that’s probably why eating chocolate boosts mood and feelings of well-being.