The correct option is A The decline in social system
According to Freud and some other psychologists the innate instinct for aggression in man is the main cause of conflicts. Thus various causes have been mentioned leading to conflicts. It arises primarily from a clash of interests within groups and societies and between groups and societies. Conflicts also ensue as a result of the difference between the rate of change in the moral norms of a society and men’s desire, hopes, dissatisfaction and demands, resulting in a decline of social system. Hence, Option A is correct.