Which of the following statements is true about information systems?

Select one:

a$.$ Total cost of ownership of information systems is often a redundant concept while making technology investment decisions.

b$.$ It is not required to plan for redundancy and disaster recovery in case of an outage.

c$.$ New programs should be thoroughly tested across the range of a firm's hardware after deployment.

d$.$ Firms need to vigilantly manage the moving target of computer security issues.

e$.$ All answers are correct.