Which of the following investments yields the highest IRR using a 15% discount rate?

a. a $500 investment that provides $100 per year for 10 years

b. a $1,000 investment that provides nothing for 5 years than cash flows $300 for the next five years

c. a $2,000 investment that provides $500 per year for 10 years

d. a $4,000 investment that provides nothing for 9 years but is redeemable for $8,000 at the end of the 10^th year

Please explain the answer.