Final answer:
The given text is likely the concluding paragraph of an expository essay, as it summarizes the main points and ends with a thought for further reflection.
Step-by-step explanation:
The paragraph provided appears to be part of the concluding paragraph of an expository essay. The function of a conclusion is to reiterate the main points presented in the essay, which is what the paragraph does by summarizing the stages of a four-stroke engine. Additionally, it leaves the reader with a final thought to consider, which aligns with the purpose of a concluding paragraph in an expository essay. In summary, a concluding paragraph must reiterate the points within your body paragraphs, complete an essay, and often closes with a statement that encourages the reader to think further about the topic.