Consider a scenario where a northbound train is approaching a southbound train that is sounding its horn. According to the Doppler effect, how will the passengers in each train perceive the sound of the horn? (A) Passengers in the northbound train should hear the true pitch of the horn; passengers in the southbound train will hear a sound lower than the true pitch. (B) Passengers in the southbound train should hear the true pitch of the horn; passengers in the northbound train will hear a sound lower than the true pitch. (C) Passengers in the northbound train should hear the true pitch of the horn; passengers in the southbound train will hear a sound higher than the true pitch. (D) Passengers in the southbound train should hear the true pitch of the horn; passengers in the northbound train will hear a sound higher than the true pitch. (E) Passengers in both trains should hear a sound that is higher than the true pitch.