Please help i will mark brainliest

as of 2019, forbes magazine has estimated the washington redskins to be worth $3.1
billion, making it the fifth most value football team. Which number represents 3.1 billion?

A) 3.1 x 10 exponent 8
B)3.1 x 10 exponent 9
c)31x10 exponent 9
d)33.1 x 10 exponent 10