Explain;
Utilitarianism - Utilitarianism is the traditional understanding that the right act is the act which will actually, or most probably produce the greatest amount of happiness or pleasure throughout the world. The view was most famously founded by Jeremy Bentham, and later adapted by John Stuart Mill. Utilitarianism focuses on the consequences of an event rather than following strict rules and in general can be classed as a type of naturalism that offers a reductionist approach to ethics.
Natural Law - Natural Law is the theory that all humans can discover what is right, due to moral being written into our nature in some way. This theory suggests that there are some absolute ethical standards are the set by the way the universe is and the way humans are. Natural law lies a great deal of importance on applying reason and science and the use of 'inherent' values such as fairness.
Situation Ethics - Situation ethics are based on the principle of love, and how all right and good actions result in the greatest amount of love as a result. Due to this, human beings should always act lovingly but the values of acting lovingly largely depend on the situation and cannot be predefined, instead the values of situation ethics are free to change in any shape or form from example as they relate the circumstances.
Proportionalism - Proportionalism is neither deontological or teleological, but rather it lies somewhere in between the two. It is an extension of Natural law, that can be easily compared with rule utilitarianism. It has moral rules (generally of the Christian variety) and says that "it is never right to go against a principle unless there is a proportionate reason which would justify it". So some things are always right or wrong, but in certain situations it could be tolerated, e.g. murder is always wrong, but there may be an exception in a just war. Toleration is not saying something is right or wrong, but rather is used to choose