Which of the description about the bronchiectasis is wrong?

A．An important diagnostic feature is the dilation of the proximal bronchi near the trachea.
B．Obstruction and chronic persistent infection are two processes crucial in the pathogenesis of bronchiectasis.
C．Bronchiectasis usually affects the lower lobes bilaterally.
D．Bronchiectasis is abnormal and irreversible dilation of the bronchial tree proximal to the terminal bronchioles.