For your ongoing business, the required investments are $420,000 for X1, $550,000 for X2, $720,000 for X3, and $900,000 for X4. X0 denotes the do-nothing alternative.

Moreover, you had information about the internal rates of return for the incremental projects:

IRR for X1-X0 is 18%, IRR for X2-X0 is 23%, IRR for X3-X0 is 17%, IRR for X4-X0 is 11%, IRR for X2-X1 is 30%, IRR for X3-X1 is 21%, IRR for X4-X1 is 27%, IRR for X3-X2 is 18%, IRR for X4-X3 is 19%, IRR for X4-X2 is 15%.

Using the information above, if the MARR is 20%, what system should be selected?