Which of the Following Statements Accurately Describes a Wave in a Closed

Which of the following statements accurately describes a wave in a closed tube (incoming wave) and a reflected wave making a standing wave?

A) The phase of a reflected wave is shifted by a half wavelength compared to an incoming wave.
B) The phase of a reflected wave is shifted by a whole wavelength compared to an incoming wave.
C) The phase of a reflected wave is shifted by a phase difference 2ð compared to an incoming wave.
D) The amplitude term has the same sign for both waves.