Writing skills – the sentence that states the main idea of the paragraph is called what?

Introduction / Context:
This question comes from basic paragraph writing and composition skills. When you write a paragraph, one sentence usually captures the central idea or main point that the rest of the sentences support. Knowing the correct term for this sentence helps you understand instructions in writing classes and exam questions about structure and organisation.

Given Data / Assumptions:

The focus is on a single paragraph, not on an entire essay or research paper.

The sentence in question states the main idea that all other sentences in the paragraph should support or explain.

Thesis is a term often used at the essay level, while topic sentence is used at the paragraph level.

Supporting detail sentences give examples or explanations but do not state the overall main idea.

Concept / Approach:
In standard writing terminology, the sentence that clearly states the main idea of a paragraph is called the topic sentence. It often appears at or near the beginning of the paragraph and guides the reader by telling what the paragraph will discuss. A thesis statement, by contrast, expresses the central idea of an entire essay or paper and is usually found in the introduction. Therefore, while both concepts are related, only topic sentence is the correct label at the paragraph level described in the question.

Step-by-Step Solution:
Step 1: Identify that the question refers to the sentence that states the main idea of the paragraph, not of the whole essay. Step 2: Recall that in paragraph structure, the main idea sentence is called the topic sentence. Step 3: Recognise that thesis is usually used for the main idea of an entire essay or research paper. Step 4: Understand that supporting detail sentences provide facts, examples, or explanations to support the topic sentence but do not state the main idea themselves. Step 5: Choose topic sentence as the only option that precisely matches the description.

Verification / Alternative check:
Consider a sample paragraph about the benefits of reading. A possible topic sentence might be Reading every day strengthens the mind and improves language skills. The remaining sentences might give examples, statistics, or explanations. At the level of the whole essay, you might have a broader thesis statement such as Regular reading is one of the most effective ways to improve personal and academic success. This thesis covers multiple paragraphs, while each paragraph has its own topic sentence. This example confirms that topic sentence is the correct term for the sentence that states the main idea of a single paragraph.

Why Other Options Are Wrong:
Option A Thesis usually refers to the main claim or argument of an entire essay, research paper, or dissertation, not a single paragraph.
Option C Both thesis and topic sentence is incorrect because the question clearly specifies the level of a paragraph, and thesis applies at a larger level.
Option D None of the above is wrong because topic sentence is exactly the commonly accepted term in writing instruction.
Option E Supporting detail sentence refers to sentences that offer evidence or elaboration, which follow and support the topic sentence rather than stating the main idea themselves.

Common Pitfalls:
Students sometimes confuse thesis and topic sentence because both deal with main ideas. A simple memory aid is to associate thesis with the whole essay and topic sentence with each paragraph. In standard five paragraph essay structures, you might have one thesis and three or more topic sentences. When exam questions mention the main idea of a paragraph, you should think immediately of the phrase topic sentence.

Final Answer:
The sentence that states the main idea of the paragraph is called the topic sentence.