Answer:
a. mobile phones
Explanation:
One day some engineers decided to change the course of history. Thinking of a way to make communication more efficient and easy, they had the brilliant idea of creating a system that would be capable of communicating between cordless phones. The idea was not bad, but the technology of the time did not help much.
The real history of the mobile phone began in 1973, when the first call was made from a mobile phone to a landline. It was from April 1973 that all theories proved that the cell worked perfectly, and that the cell phone network suggested in 1947 was designed correctly. This was a not very well known moment, but it certainly was a fact marked forever because it was the moment that facilitated communication for most people through the creation of the mobile phone.
Watch this video https://www.youtube.com/watch?v=ce-v8rcFPlA
They are both greatest anciest civilizations in history, and yet we know very little about them compared to other parts of the world. The Inca's were in Peru, The Aztects were in modern-day Mexico
<span>since brazil needed workforce and the natives were not wanting to the enslaved african americans from africa and they didn't know how to work on a different terrain so the brazzilian people trained them on what to do
i hope this helps you out</span>