Final answer:
A computer can become infected with viruses through downloading and opening unknown files, but not by simply creating a new folder on the system.
Step-by-step explanation:
A computer can become infected with viruses in several ways, but creating a new folder on your computer is not one of them. Viruses typically infect computers through actions that involve downloading or executing unknown or unsafe files. For example, opening attachments to e-mail messages, downloading software from the Internet, and downloading files from the Web are all common ways for a computer to get a virus. However, simply creating a new folder does not expose a computer to viruses as it does not involve executing or downloading files from an untrusted source.