Which fact most effectively supports the claim that PGP can be used by an ordinary person?

PGP works efficiently on a personal computer.

Explanation:

Since PGP can work efficiently on a personal computer with just the push of a button, it makes it very easy to use by an ordinary person. That ordinary person may not understand the mathematics or the digital encryption so these are not good options. The article talks about how the ordinary person can put PGP on their personal computer and it will automatically incorporate a digital signature and encrypt an email with the touch of a button. This way anyone can use it.