Answer:
social contract in political philosophy an actual or hypothetical compact or, agreement between the ruled and their rulers defining the rights and duties of each ... they seen by exercising natural reason formed a society ( and a government) by means of a contract among themselves
B. Mt. McKinley! It’s 20,237 feet!
One of the most significant challenges is building an airplane had to do with "propulsion", since the technology that allowed motors to have enough energy to lift an airplane into the sky with a passenger wasn't available for most of history.
