What two things made it possible for explorers to travel all over the world in sailing vessels

The two things that made it possible for explorers to travel all over the world in sailing vessels were the apparition of a new type of ship called "the caravel" and a new device called "magnetic compass".

Explanation:

The Caravel was a ship that had many uses. These ships were from small to medium. They could be used as cargo ships, warships, patrol or dispatch boats and also pirate ships. They were mainly used for fishing. The Caravel was from 50 to 200 tons. These ships were cheap and you could get them in shape for working very easily. They were known for their speed and maneuverability. So these ships were used by explorers to explore.

The compass helped indicate North, South, East and West. It was used to navigate them in the right direction. The direction in which the compass pointed to, related to the Earth's magnetic poles. the compass improved the safety and efficiency of travelling, especially by sea.  

answer; /// i believe the three where,tutankhamun,hatshepsut and , im not sure,but maybe (ramses the great)

c.) the country needed a stronger central government.