Convert to Scientific Notation

Scientific notation is a method of expressing numbers that are too large or too small to be conveniently written in decimal form. A common format for scientific notation is $a imes 10^n$, where $1 \leq a < 10$ and $n$ is an integer.

Convert the following number, 6,500,000,000, into scientific notation. Which of the following represents the correct scientific notation for this number?