Because it's less dense than liquid water.
I think the word you're looking for is "hypothesis".
For example, a hypothesis could be "dogs drink more often when owners are present".
And then this can be proven (or dis-proven) by an observation (or in this case rather: measurement).
Answer:
AUTEUR
Explanation:
AUTEUR, the French translation for author is also used to denote an artist. The term describes directors and filmmakers who are responsible for controlling many aspects of a creative work. An Auteur possesses a single vision and consistent individual style that makes his work unique.
Because the mud was rich and held strong since Mesopotamia was the "land between the rivers". The mud was from the banks of the yufrates and tigres river. (Check my spelling on the rivers)