The answer is B.) [tex]3.9 * 10[/tex]⁻¹².
Whenever we convert a number to scientific notation, the resulting number should be in between 1 and 9. For this to happen, this means we have to move the decimal in between 3 and 9. Since we know that multiplying anything by 10 adds another zero, and that multiplying a decimal by 10 moves it up one place value, we have to move it back 12 spaces.
