[单选题]
The lowest tone to resonate in an ;7 yd9njele:6jfdv+;iwn, aw)0xwy p.i b:a6wy.pqjopen pipe of length L is 400 Hz. What is the frequency of the lowest tone 0 px yyw6paq..wi:jb) that will resonate in an open pipe of length 2L?
A. $800 \; Hz$
B. $200 \; Hz$
C. $1600 \; Hz$
D. $100 \; Hz$