Simon has linked her digital music player wirelessly to the speaker system in her car. how is the data exchange between her music player and her car system?

The data exchange is happened using the radio waves around these paired devices.

Explanation:

The wireless electronic devices are connected or paired with each other by enabling the Bluetooth menu. The Bluetooth works using the radio waves. Bluetooth is nothing but wireless and short range device which connects the short range devices. The radio waves generated in this device enable the other device to pair with it. Hence, there is a transfer of data happens with these paired devices. The radio waves act as a medium to transmit the audio files hence, the music plays.