Which of the following is a way the operating system prevents unknown or unauthorised users from accessing the system?

You need a reliable network for about twenty-five computers that will be distributed across a large building. it is important that the network be relatively cheap. which topology should you use?

Melissa needs to add a topic to an email that she will send to her teacher. choose the name of the field where she should type her topic.

Can someone work out the answer as it comes up in one of my computer science exams and i don't understand the cryptovariables