Please help someone. Saturation divers who spend days or weeks under water often breathe a mixture of helium and oxygen. One side effect of this gas mixture is that it makes the divers' voices higher-pitched. What is the cause of this increase in pitch?
a. Sound waves travel slower in the helium-oxygen mixture, resulting in a higher frequency for the same wavelength.
b. The helium-oxygen mixture decreases the amplitude of the waves, which increases their frequency.
c. Ultraviolet, X-rays, gamma rays, and sound waves travel faster in the helium-oxygen mixture, resulting in a higher frequency for the same wavelength.
d. The helium-oxygen mixture increases the amplitude of the waves, which increases their frequency.