You have a choice between two mutually exclusive investments:

a: year $0=-400,$ year $1=241,$ year $2=293,$ IRR$(\%)=21$

b: year $0=-200,$ year $1=131,$ year $2=172,$ IRR$(\%)=31$

The opportunity cost of capital $9\%,$ you are tempted to pick B$,$ which has a higher IRR, why is project B not the right option?