Well we know that it is not A or C, Reason: Some states have up to 5m people in it. (For example about 8 live in just new York alone.)
And we also know its not 10 billion. Reason for this: Scientist have proven that there is no more then 8 billion people today.
And so now we got 6.5 billion is the closest, the real number is about 7.5 billion.
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The effects that WWI had on Germany was that they lost allies and suffered huge territorial losses giving away its land and population to Poland, Russia, France, Belgium, and Denmark, and ultimately had to sign the Treaty of Versailles. After the U.S involvement in the first World War it lead directly to the Great Depression and WWII, The Treaty of Versailles led to a system where the U.S was cashing in its wartime loans to the U.K which in turn was using the wartime reparations it received from Germany to pay off the U.S.
The answer to your question is D. Ferdinand and Isabella sponsored his first voyage<span />
It is important to wash your hands so you can prevent yourself from getting diseases and/or giving someone else them in return. Another reason is to prevent yourself from getting the flu and other sicknesses. Plus it is good hygiene and makes for good habits and cleanliness