Instead of having one backup module, consider having two backup modules. (Hence, you have three modules in the system: A, A, and A). Assume there is no correlation among three modules and each backup module has the same reliability of 90%. What is the reliability of the server?

a

0 (=0%)

b

0.001 (=0.1%)

c

0.1 (=10%)

d

0.9 (=90%)

e

0.999 (=99.9%)

f

No correct answers above