Answer:
Let's take a look at the modern day headphones we have now. They're airpods. Wirless. It used to be connected to wires. And those earbuds used to be headphones. And those headphones used to be heavy speakers.
Explanation:
How did they evolve with growth in technology? Back in the early 1890s, headphones were single-sided, heavy speakers that people would hold on to an ear to communicate. This later evolved into something known as an 'Electrophone'. It was a system consisting of a stethoscope-shaped headphone connected to a switchboard.
We started using them in the wars to communicate with the troops on the ground and now we use them to stay focused, to disappear and to give ourselves some time away from the stressful world we live in.
Answer is C. Deegeees north and south of the equator
A thermocline is the transition layer between the warmer mixed water at the surface and the cooler deep water below. It is relatively easy to tell when you have reached the thermocline in a body of water because there is a sudden change in temperature.
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Mining
The Pacific islands have a great amount of minerals
The proximity of water was an advantage to Western Europe and its culture was able to flourish as a result. Trade and travel by sea were easier and safer in historical times.