An ultrasound machine is calibrated in a laboratory at 25 °C to emit pulses at 6.00 MHz; the wavelength in tissue at that temperature is critical for image resolution. During surgery the patient’s body temperature rises so that the speed of sound in tissue increases by 1.5 %. To maintain the original wavelength, what frequency should the machine now use?
a) 5.91MHz
b) 6.90MHz
c) 6.09MHz
d) 6.00MHz