Why was the invention of the magnetic compass important?

It made navigation much, MUCH easier.

Explanation:

Normally, people relied on staying  close  to the shore to avoid getting lost. Only the bold would go out farther.  But with the invention of the  magnetic compass- you could go much further as you had a sense  of direction.  You could still get lost,  but you could likely find your way back.

c it says nothing about connecting those 2 seas.

hello there the answer is a

sorry if i am wrong hope that : )