You can invest $3,000 at the end of each of the next 20 years into a retirement account paying 10% annual interest. Alternatively, you can enter into a retirement plan with your employer where, for every yearly (end-of-year) payment of $3,000 you make, the firm will contribute $1,500. Your employer's plan will also last for the next 20 years. The firm guarantees a return of 7% on its retirement plan. Which option is better?