In the following paragraph there are two conceptual mistakes. Please find them. "The Doppler effect is based on the work of physicist Christian Doppler. The effect describes a change in the frequency and in speed of a sound wave resulting from relative motion between the sound and the sound receiver like a listener. When there is no motion between the source and the receiver the frequency of the sound wave is constant. If the sound source instead moves toward the receiver, the sound waves is stretched, and a higher pitch sound occurs." Select all correct answers: A. Row 4: the sound wave is squeezed not stretched when the source moves toward the receiver. B. Row 3; the frequency of sound is only changing when there is no motion between the source and the receiver. C. Row 4: the pitch is lower when the source is moving toward the receiver. D. Row 1: the speed of the sound wave is not changing. E. Row 1: the frequency does not change only the wavelength changes.