Answer: Classified as a theory.
Explanation: The dictionary definition of theory is a system of ideas that are used to logically explain something. It also says that they are also based off of something not entirely connected to the thing the theory is being made about.
Because the idea that the universe has expanded explains such a large number of observations, which in turn leads to more predictions and therefore more observations that support it, this becomes your system of ideas. Because this system was based off of the aforementioned observations in the first paragraph, this proves that it is best classified as a theory.
There are many reasons to why slaves were essential in the colonial economy:
Slaves were generally used more in the south, because large plantations were found there, which meant that the need for large amounts of workers.
Slaves provided cheap labors, and as they were not "citizens" of the US, they were not allowed their rights.
Slaves were also relatively easy to buy and replace, however, their survival rates were not that good after they traveled long distance.
etc.
hope this helps
Studies of populations that reveal correlations between dietary habits and disease incidence are epidemiological studies.
Answer:
water
Explanation:
Water puts out fire by creating a barrier between the fuel source and the oxygen source (it also has a cooling effect which has to do with the energy required to convert liquid water into water vapor). It does this because it is a completely, 100% oxidized material. It simply cannot oxidize any further so it will not “burn”. This smothers the fire. The same thing would happen if you used the ashes that remained after a completely spent fire. Or, as I mentioned before, CO2.
A vaccine works by training the immune system to recognize and combat pathogens, either viruses or bacteria.