A certain string, clamped at both ends, vibrates in seven segments (half wavelength loops) at a frequency of 2.40 × 102 Hz. What frequency will cause it to vibrate in four segments?
A89 Hz (c) 274 Hz (e) 420 Hz
B137 Hz (d) 411 Hz
A89 Hz (c) 274 Hz (e) 420 Hz
B137 Hz (d) 411 Hz