At the end of the 20th century, the world's population was approximately\[6.125\times {{10}^{9}}\]. Express this population in usual form.

• A.  \[6.125\times {{10}^{10}}\]           
• B.  6125000000
• C.         \[6125\times {{10}^{5}}\]  
• D.         612500000