6 As a result of using various investment appraisal techniques, a firm has established that machine A has a payback period of 4 years, machine B has a negative internal rate of return of 6%, machine C has a net present value of £50,000 and machine D has an accounting rate of return of 8% p.a. Based on this information alone, which one of the machines would appear to be the least favoured investment?

(a) Machine A

(b) Machine B

(c) Machine C

(d) Machine D