Explanation:

- Biology and Science: Biology is a branch of science. It deals with the study of living organisms, making it one specific field within the broader category of science.

- Political Science: This is a branch of knowledge that deals with systems of government and the analysis of political activity and behavior.

- Option 1 - Politician: A politician is a person involved in politics, not a category of knowledge.

- Option 2 - Social Science: Political Science is a sub-discipline within the Social Sciences, making this the correct answer.

- Option 3 - Languages: Languages is a branch of study but not directly related to political science.

- Option 4 - Earth Science: Earth Science is another branch of science but unrelated to political science.