[单选题]
When a light wave entoh q/fs4 (tx 4 i) aaa(mzs:j54dj6woq/ v6/ qcbu/xve 7m(ujlers into a medium of different optical density,
A. its speed and frequency change.
B. its speed and wavelength change.
C. its frequency and wavelength change.
D. its speed, frequency, and wavelength change.