Whenever people are together, there may be some argument or disagreement. What we want sometimes conflicts with what other people want. This happens to our family, friends and our communities.
Sometimes there is a breakdown in a relationship and people fight and refuse to talk to each other. But wise people know that this causes great pain and difficulties so they talk about their problems and try to understand the other problems and other people's wishes. Understanding doesn't mean agreeing. It means looking for the other person eyes and standing in other person shoes. Then it is possible to come to an agreement with both sides changing a little and good relationship continues.
There is often conflict between countries. This is usually about control and ownership of land or natural resources, e.g. Kashmir is claimed by both India and Pakistan. Israel and Palestinians also have a dispute over land. Sometimes there is revenge for the way a country citizens have been treated, sometimes a leader wants to gain power by encouraging aggression other countries.
These days many countries have large weapons, which can destroy cities and kill many people. Missiles fly like airplanes and can hit and destroy targets. Powerful bombs can be dropped. Atom bombs dropped on Japanese cities of Hiroshima and Nagasaki during World war II caused unbelievable loss of life and property. Rifles and guns have long ranges and rate power because there are many types of people and their aspirations, conflicts exist as long as human society exists. The more we can manage to minimize their conflicts the more can we be benefited. Therefore, countries need to understand each other and try to maintain relationships.
a. No, people are not born knowing what is wrong and wright.