At First, thE spEAkEr wAs rEFErring to thE proBlEm oF pollution in thE Country, But hAlFwAy in hEr spEECh, shE suDDEnly ______ to AnothEr suBjECt.
A、CommittED B、switChED
C、FAvourED
D、trAnsFErrED