[单选题]
In a resonating pipe wh,l(gxdngm. 7r ich is open at both en+g,r.j n my3b3whyri-ds, there
A. are displacement nodes at each end.
B. are displacement antinodes at each end.
C. is a displacement node at one end and a displacement antinode at the other end.
D. none of the above
