Why was the invention of the magnetic compass significant?

The magnetic compass was an important advance in navigation because it allowed mariners to determine their direction even if clouds obscured their usual astronomical cues such as the North Star. It uses a magnetic needle that can turn freely so that it always points to the north pole of the Earth's magnetic field.

Explanation:

1) the answer is b

senators serve a six-year term; representatives serve a two-year term, making them more responsive to (and responsible for) voter confidence.

2) the answer is d

to serve as president, one must:   -be a natural-born u.s. citizen of the united states;   be at least thirty-five years old;   be a resident in the united states for at least fourteen years.

3) the answer is a

ella,because it is constitutionally eligible

4) the answer is c: the u.s president

these civilizations were located around fertile rivers, where they could produce an abundance of crops