A sound recording is made of a train as it blows its whistle for 10 seconds. The pitch of the sound appears to be decreasing during the 10 seconds. What conclusion, if any, could be made about the motion of the train and how do you justify this conclusion?

Which best describes how fluids change as they travel through different portions of the convection currents? they change to solids at the outer portion of the convection currents. they change to solids at the inner portion of the convection currents. they become more dense at the outer portion of the convection currents. they become more dense at the inner portion of the convection currents