You invest $10,000 in a complete portfolio. The complete portfolio is composed of a risky asset with an expected rate of return of 10% and a standard deviation of 21% and a treasury bill with a rate of return of 4%. How much money should be invested in the risky asset to form a portfolio with an expected return of 7%?

A) $6,000

B) $5,000

C) $7,000

D) $4,000