Which component would you find in the physical layer of the network protocol stack?

The physical layer of the network protocol stack is responsible for the actual transmission of raw bitstreams over a physical medium. This includes the hardware technologies associated with transmitting data over a network, such as cables, switches, and wireless radio frequencies. WiFi fits this description as it refers to a wireless networking technology that enables devices to connect to a network using radio waves.

In contrast, the other options are protocols that function at higher layers in the network protocol stack. TCP (Transmission Control Protocol) operates at the transport layer and is responsible for ensuring reliable data transmission between devices. FTP (File Transfer Protocol) works at the application layer, enabling users to transfer files across the internet. HTTP (HyperText Transfer Protocol) is also an application layer protocol used for transmitting web pages and online content.

Thus, WiFi is the only choice among them that pertains directly to the physical layer, as it involves the transmission technology utilized for network communication.