Answer:
Renewable energy is growing fast in the U.S., but fossil fuels still dominate. Most Americans (77%) say it's more important for the United States to develop alternative energy sources, such as solar and wind power, than to produce more coal, oil and other fossil fuels, according to a recent Pew Research Center survey
Only 200 out of 2 000, 000 sperm cells reach the ovum. And only one (in exception to very rare cases of two) sperm cells actually participate in the process of fertilization. In comparison, an average female only produces 400 of egg cells during their lifetime, but the eggs cells are significantly larger than sperm cells.
“Neuron” is another name for a nerve cell.
Given that,
The speed of a wave, v = 200 m/s
Wavelength, 
We need to find the frequency of this wave. The relation between wavelength, frequency and the speed is given by :
So, the frequency of this wave is 100 Hz.
