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.
The answer would be b. State identification card
Answer:
They allowed Portuguese and Spanish navigators to sail across oceans rather than only along the coast.
Explanation:
Confucianism should be the answer. Confucianism had many beliefs about hierarchy of people and was all about respecting your superiors and being respected by your lower ones.
Celsius, people in Europe would use Celsius
