The following table shows the time between failures (in hours) observed for a piece of software:

Error number	1	2	3	4	5
Time since last failure (hours)	6	4	8	5	6

Assuming an exponential reliability model, what is the reliability of the system for one hour of operation?

1. A(A) e^(-9/29)
2. B(B) e^(-7/29)
3. C(C) e^(-5/29)
4. D(D) e^(-3/29)

Pick an option to check yourself, or open the answer below.