Answer:
Option (D) is correct.
Step-by-step explanation:
The payback period is the amount of time required to get your investment back. 
 Shorter the payback period, the better it is for the investor.
Given that,
Useful life = 6 years
Copier cost = $7,740 
Generate annual cash inflows = $2,150
Therefore,
Payback period = Initial investment ÷ Annual cash inflow 
 payback period = $7,740 ÷ $2,150 
 = 3.60 years