How do graph this and cash flows in general?

Given the following cash flow plot NPV vs i and tell me how many roots you find and where. Year Cash Flow 0 1 2 3 -$1,000 E $3,600 -$4,280 $1,680 a. roots at 3%, 16 and 28% O b. roots at 0%, 20% and 40% C. roots at 5%, 10% and 15% O d. roots at 0%, 30% and 60%