Jack and Jill are both moving with the same velocity $($same speed in the same direction$).$ A stationary sound source is between them so that Jack is moving away from the source and Jill is moving towards it$.$ Which of the following is correct?

Compared to the emitted frequency, Jack hears a higher frequency and Jill hears a lower frequency.

Compared to the emitted frequency, Jack and Jill both hear a lower frequency.

They hear the same frequency because they have the same speed.

Compared to the emitted frequency, Jack hears a lower frequency and Jill hears a higher frequency.

Compared to the emitted frequency, Jack and Jill both hear a higher frequency.