The correct answer is D. By describing an example of how money could be stolen and sent abroad
Step-by-step explanation:
In the excerpt presented, the author explains a hypothetical situation in which a bank is asked through e.mail to transfer the funds of a client to a different bank account, about this, the author remarks as e-mails do not have a handwritten signature it would not be possible for the bank to know whether the e-mail is written by the owner of the account or a criminal and then ends the text with the main claim or idea that is "it is essential that there is some form of reliable digital signature", this means the information presented before the claim support this by providing a hypothetical situation or an example of the consequences of not having a reliable digital signature and the way money could be stolen as a consequence. Therefore, the author supports the claim by describing an example of how money could be stolen and sent abroad.