Answer:
A.) Project A only
Explanation:
Given that
For project A
Pay back = 2.9 years
Net present value = $4,200
For project B
Pay back = 3.1 years
Net present value = $26,400
Based on the above information and payback decision rule, The project A should be accepted as it it contain less period compared to the project B i.e 2.9 years to 3.1 years
Hence, the correct option is a.