In 2007, computer scientist Luis von Ahn was working on converting printed books into a digital format. He found that some words were distorted enough that digital scanners couldn't recognize them, but most humans could easily read them. Based on that finding von Ahn invented a simple security test to keep automated "bots" out of websites. The first version of the reCAPTCHA test asked users to type one known word and one of the many words scanners couldn't recognize. Correct answers proved the users were humans and added data to the book -digitizing project. Which choice best states the main purpose of the text? A) To discuss von Ahn's invention of reCAPTCHA B) To explain how digital scanners work C) To call attention to von Ahn's book -digitizing project D) To indicate how popular reCAPTCHA is

## Step 1<br />The first step in solving this problem is to understand the main idea of the text. The text discusses Luis von Ahn's invention of reCAPTCHA, a security test designed to differentiate between humans and automated bots on websites.<br /><br />## Step 2<br />Next, we need to analyze each of the given options in relation to the main idea of the text.<br /><br />### Option A<br />This option states that the text discusses von Ahn's invention of reCAPTCHA. This aligns with the main idea of the text, which is about the invention of reCAPTCHA.<br /><br />### Option B<br />This option suggests that the text explains how digital scanners work. However, the text does not delve into the workings of digital scanners, but rather focuses on the problem that digital scanners face with certain distorted words.<br /><br />### Option C<br />This option suggests that the text calls attention to von Ahn's book-digitizing project. While the text does mention this project, it is not the main focus of the text.<br /><br />### Option D<br />This option suggests that the text indicates how popular reCAPTCHA is. However, the text does not provide any information about the popularity of reCAPTCHA.<br /><br />## Step 3<br />Based on the analysis, we can conclude that option A is the most accurate choice as it aligns with the main idea of the text.