Answer: Alternative 3 will be selected.
Step-by-step explanation:
The system that should be selected is the alternative that is better than the other alternatives by being higher than MARR if selected.
First compare A1 to A0
The rate of return here is 18% which is higher than the MARR of 15% so Alternative 1 should be chosen over A0 which is to do nothing.
Compare A1 to A2
If A2 is chosen over A1, the incremental return is 10% which is less than the MARR of 15% so A2 should not be chosen over A1. A1 should instead be chosen over A2.
Compare A1 to A3
If A3 is chosen over A1 then the incremental return would be 18%. This is higher than the MARR of 15% so Alternative 3 should be chosen over Alternative 1.
Alternative 3 should be chosen over A1 which should be chosen over A2 and A0.
A3 will therefore be selected.