In an essay it should only be one I'm pretty sure, but in a narrative as many as it takes to explain a lesson learned. If you were writing a book your conclusion would be whatever comes to you and whatever you feel the characters would do/say/feel.
The pine trees shuddered in the snow
Answer:
✓More than a hundred million e-mails are sent around the world each day, and they are all vulnerable to interception.
✓Other attacks include the use of viruses and Trojan horses.
✓Only a small fraction of the information flowing around the world is securely encrypted. :)
