Research has shown that many business offices are facing large numbers of humorous e-mails in their inboxes. Even though these messages are often found to come from individual employees who have forwarded them to the entire staff, these employees are very rarely found laughing at the contents of the e-mails before forwarding them. This does not mean that these employees do not find the e-mails amusing, though, since _______________ .

Which of the following most logically completes the argument?

_______.