the isotope they use is carbon-14
C or b is the correct answer
The formula F=velocity/wavelength
F=24/2
F=12 Hz
0.9 is less than 1.0 by 0.1
so your answer is true
hope this helps
The term for the disturbed water left behind as a boat moves through the water is
wake.
When a boat glides through any type of water, it will sort of separate the water behind it for a few seconds, after which the water will return to normal once again. I've attached the image so that you can see clearly what I'm talking about.