Which word indicates an act done for one's own advantage?

The word that best indicates an act done for one's own advantage is "expedient." This term refers to a course of action that is convenient and practical, often at the expense of ethics or principles. In various contexts, an expedient action is typically taken to achieve a specific goal or benefit, thereby serving one's own interests, even if it is not the most ethical choice. This self-serving aspect is what makes "expedient" the correct answer.

In contrast, "exculpate" means to clear someone from blame; it does not imply self-advantage. "Extempore" describes something done spontaneously or without preparation, which does not inherently relate to personal benefits. "Expropriate" refers to the action of taking property from its owner for public use, which may involve advantage but does not encapsulate the self-serving nature implied by "expedient." Hence, within this context, "expedient" stands out as the term that best signifies acting for one's own advantage.