Which of these factors best explains why liquid water exists on earth ? a. weak salinity of earth oceans b. earth strong gravity c. presence of living things on earth d. freezing temperatures at earth poles the answer is b and this for apex

The "right" answer would be something like

"The temperature of the earth is such that permits the existence of liquid water"

Now let's analyze the option that can mean this:

The b option "Earth strong gravity" is related to the mass of the earth, and the mass of the earth is, in some way, what defines the orbit that Earth has around the sun.

So if the orbit of earth was closer to the sun, the liquid water would boil, and if the orbit was further away from the sun, the liquid water would freeze.

Then the option b is the one that best explains why liquid water exists on earth.

k2s for potassium sulphide