Your grandfather started his own business 45 years ago. He opened a savings account at the end of his sixth month of business and started contributing $x from then on every six months. His savings account has paid an average interest rate of 6 percent per year. Today, his account is valued at $133,004.67 How much did your grandfather save every six months?

A. $250 B. $300 C. $350 D. $400 E. $450