A String That Is 0 $0.88 \mathrm {~m}$ Long and Open at Both Ends into Its Second Overtone

Multiple Choice

A string that is 0.26 m long is vibrating in its n = 6 harmonic.The sound from this string excites a pipe that is $0.88 \mathrm {~m}$ long and open at both ends into its second overtone resonance.What is the common resonant frequency of the string and the pipe? The speed of sound in air is 345 m/s.

A) 590 Hz
B) 390 Hz
C) 490 Hz
D) 690 Hz
E) 760 Hz