What is the primary purpose of an introductory paragraph?

The primary purpose of an introductory paragraph is to catch the reader's attention and introduce the topic. This opening section serves as a way to engage the audience right from the beginning, making them interested in reading further. In providing a hook—such as an intriguing question, a relevant quote, or a striking fact—the introductory paragraph sets the tone for the entire piece.

Additionally, this paragraph typically includes a thesis statement, which outlines the main argument or point that the essay will develop. By clearly presenting the topic and the essay's direction, it effectively prepares readers for what to expect in the body paragraphs. This is why option B stands out as the correct choice, as it encompasses both the role of engagement and the introduction of the topic, which are essential for any successful opening in an essay.

The other options focus on elements that are not typically found in the introduction. Summarizing main points, providing detailed background, and presenting conclusions are tasks that belong elsewhere in the essay, particularly in the body paragraphs and the conclusion, indicating those choices do not align with the primary function of an introductory paragraph.