Which of the following connections is made between a computer and a transceiver to use computer software when operating digital modes?

When setting up a computer for digital modes, you need to route the audio heard by the radio into the computer so the software can decode it. The transceiver's speaker connector (or a dedicated audio out port) provides this received audio. This audio must go into an input on the computer's sound card. The computer's "line in" (or microphone input) is the correct jack to receive this incoming audio signal. Connecting a computer's "line out" to a speaker connector or push-to-talk is incorrect, as "line out" is an audio output that needs to go to the radio's microphone input, not its speaker or control lines.