Realism is the dominant and  most effective framework today to explain world politics. However, it does have both strengths and weaknesses when used in the real world because it is a theoretical account of how the world works. Realism has been criticized for being too focused on higher-level political analyses, for the centrality it places on the unit of the state, and for its reliance on human nature, ego and emotion. As also understood from the information given the correct answer is D.

Realism as a perspective cannot explain everything. As Kenneth Waltz indicated, the contribution of realism to international relations lies is telling us “a small number of big and important        things” . What is mentioned in the last option has not been considered as a critics. Telling us “a small number of big and important things” has been indicated as a contibution.