[单选题]
A 3.00-m long pipe is in csy5jkk/ra-n0 chnl8 s 5s*2ua room where the u -96eo 1pg xoijj4u+ptemperature is $20 \; ^{\circ}C$. What is the frequency of the second harmonic if the pipe is closed at one end?
A. $57 \; Hz$
B. $114 \; Hz$
C. $29 \; Hz$
D. none of the above