Textbooks represent an 11 billion dollar industry, up from $8 billion in 2014. Textbook publisher Pearson is the largest publisher—of any kind—in the world.

    It costs about $1 million to create a new textbook. A freshman textbook will have dozens of contributors, from subject-matter experts through graphic and layout artists to expert reviewers and classroom testers. Textbook publishers connect professors, instructors and students in ways that alternatives, such as open e-textbooks and open educational resources, simply do not. This connection happens not only by means of collaborative development, review and testing, but also at conferences where faculty regularly decide on their textbooks and curricula for the coming year.

    It is true that textbook publishers have recently reported losses, largely due to students renting or buying used print textbooks. But this can be chalked up to the excessively high cost of their books—which has increased over 1,000 percent since 1977. A restructuring of the textbook industry may well be in order. But this does not mean the end of the textbook itself.

    While they may not be as dynamic as an iPad, textbooks are not passive or lifeless. For example, over the centuries, they have simulated (模拟) dialogues in a number of ways. From 1800 to the present day, textbooks have done this by posing questions for students to answer inductively (归纳性地). That means students are asked to use their individual experience to come up with answers to general questions. Today’s psychology texts, for example, ask: “How much of your personality do you think you inherited?” while ones in physics say: “How can you predict where the ball you tossed will land?”

    Experts observe that “textbooks come in layers, something like an onion.” For an active learner, engaging with a textbook can be an interactive experience. Readers proceed at their own pace. They “customize” their books by engaging with different layers and linkages. Highlighting, Post-It notes, dog-ears and other techniques allow for further customization that students value in print books over digital forms of books.

解析：B。根据experts和students using textbooks可定位到原文最后一段。最后一段第二句指出，对于一个积极的学习者来说，阅读课本是一种互动的体验。题干中的students using textbooks对应learner和engaging in textbooks，B项中的interactive在原文中复现。随后在第三句继续指出，读者可以按自己的节奏阅读，他们可以通过使用不同的层次划分和联系来“自定义”他们的书籍。B项中的learn in an interactive way是对该句内容的概括，故B项正确。原文最后一段只是说使用纸质教科书学习的优点，A项中的关键词digitalize在原文中并没有提及，故A项可排除。C项用customized设置干扰，但原文中的customized指的是学习方法而不是教科书本身，故C项错误。原文最后一句说到，纸质书可以进行进一步的“自定义”，学生可以在书上做各种记号，这并不等同于D项所说的学生可以自己适应学习材料，故D项排除。