Which of the following is TRUE for an open-ended resonant air column? A. It resonates only at odd-numbered harmonics (ie. n= 1,3, 5, ...). B. It resonates only at even-numbered harmonics (ie. n =2, 4, 6, ...). C. It resonates at any whole-numbered harmonic (ie. n =1, 2, 3, ...). D. Nodes are found at both ends of the air column.

Fig: 1

Fig: 2

Fig: 3

Fig: 4

Fig: 5