[单选题]
A sound source departs fromitytgs4 0 lsemro85d*62nl 6 g a sy 6h9kb,6mk ;32oavtn nnhtj.tationary observer. The frequency heard by the observer in6o.na ,t jh3nk2mbhkyt6v9; s
A. higher than the source.
B. lower than the source.
C. the same as that of the source.
D. equal to zero.
