Joe, an employee, wants to show his colleagues how much he knows about smartphones. Joe demonstrates a free movie application that he installed from a third party on his corporate smartphone. Joe's…

Near-field communication (NFC) is a short-range wireless communication technology used for data transfer and payments, not a method for installing unauthorized applications.

Rooting (Android) or jailbreaking (iOS) removes the manufacturer's and OS vendor's security restrictions, allowing the installation of apps from outside the official app store and granting elevated privileges that would otherwise be blocked by the platform's security model.

Ad-hoc connections refer to peer-to-peer wireless networking between devices and are not a mechanism for bypassing app store restrictions or installing third-party applications.

Tethering is the practice of sharing a device's internet connection with other devices and has no relevance to the installation of unauthorized or third-party applications.

Sideloading is the process of installing an application directly onto a mobile device from an unofficial source (outside the sanctioned app store), which is exactly what Joe did by obtaining and installing a free movie app that was not available through official channels.