Over two summers, Ray saved $900 and $500. The polynomial 900x 2 + 500x represents his savings at the beginning of the third year, where x is the growth factor. (The interest rate r is x - 1.) What is the interest rate he needs to start the third year with $1600 in savings?

A. 8.4%
B. 264%
C. 0.1%
D. 1.1%