For the people that can't see the picture Which of these forces is responsible for attracting the opposite poles of two bar magnets towards each other?

Gravitational force

Electromagnetic force

Weak nuclear force

Strong nuclear force

The correct answer is Electromagnetic.

Explanation:

Gravitation force is what holds the planets on their axis. Weak and Strong Nuclear force have to do with Nuclear energy of some kind. Making electromagnetic the correct answer.

not only is it colder, it also becomes darker, less salty, and more dense.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.