The person that hears the train horn at a lower pitch is the person C.
In sounds, pitch refers to how high or low a sound is. This often depends on the wave oscillation because a higher oscillation means the sound is high. Moreover, the pitch can be different depending on the location of the listener.
One of the factors that can slightly change the pitch is the distance between the source and the listener. In this context, distance can make the pithc lower as it decreases wave frequency.
Based on thiss context, it is likely the person C hears the sound at a lower pitch because this person is the farthest from the source and this person is not moving towards the source as it occurs with person A.
Learn more about the pitch in: https://brainly.com/question/27128408