In the passage, the author states that distributing a document on the Web is similar to recording an outgoing message on a telephone answering machine. The author argues that a third party creating and distributing a link to a document placed on the Web is similar to distributing someone else's phone number; anyone can access the document or outgoing message, but it is the original distributor (i.e. the individual who uploaded the document or recorded the outgoing message) who controls overall access.
Similar to requesting an unlisted number and being selective with the distribution of one's phone number, individuals can restrict access to the documents they have uploaded by, for example, requiring a password. The author of this passage argues that this restriction of access to online information would, to some degree, compromise the openness of the Web, but that this is far less threatening to the online exchange of information than the threat of copyright infringement litigation.
While the author does discuss telephone answering machines as part of an analogy, it is not for the purpose of illustrating the positions taken by each side in the copyright debate. Rather, it is to argue in favour of one particular outcome for the copyright debate: requiring owners of intellectual property to individually restrict access to their property at their own discretion as opposed to changing copyright laws more broadly.
This is why B is incorrect and D is the correct answer choice.
Hope this is helpful! Please let us know if you have any further questions.
