Which of the following is a digital communications mode?

Packet radio is a classic amateur digital mode used to send data in discrete bundles (packets) over RF. FT8 is a highly popular, modern weak-signal digital mode used extensively on the HF bands. IEEE 802.11 is the standard name for Wi-Fi, which might not immediately sound like a ham radio mode, but amateur operators frequently use 802.11 equipment on microwave bands to build high-speed multimedia mesh networks (like AREDN). Because all three are valid digital communications modes used in amateur radio, 'All these choices are correct' is the right answer.