Final answer:
The controlling idea of an essay is represented by the term 'Topic'. It is closely related to the thesis statement, which is supported by topic sentences in the body paragraphs. These elements work together to form the cohesive argument of the essay.
Step-by-step explanation:
The term that represents the controlling idea of an essay is a) Topic. The topic refers to the main subject that the essay discusses, and it is typically embedded in a thesis statement, which conveys the essay's central argument or position. The thesis statement is supported by topic sentences, which are the major supporting statements for the thesis found in the body paragraphs.
Each topic sentence should relate back to the thesis statement by presenting the main idea or point the paragraph will discuss or argue, providing a roadmap for the reader. Furthermore, the paragraph will contain evidence, such as quotations, paraphrases, or summaries from sources, which supports the point made in the topic sentence. This supporting evidence should be synthesized appropriately to demonstrate how it backs up the topic sentence's claim, thereby collectively supporting the overarching thesis of the essay.
These core components—topic sentences, evidence, and analysis—create a cohesive and persuasive argument throughout the essay, giving it structure and clarity. They ensure that each paragraph contributes to the overall purpose of the essay, which is to prove or illustrate the thesis statement through logical reasoning and substantive evidence.