Choice "B" is correct. Downtime (or the complete lack thereof) is a key factor in the disaster recovery plan. Backup is always essential in any disaster recovery plan. Choice "B" is the only choice with both downtime and backup. Choice "d" is incorrect. Backup is always essential in any disaster recovery plan. These days, data transmission is an integral part of normal processing and of disaster recovery, and data transmission would definitely be important in any disaster recovery plan (normal data transmission has to be re-established at the disaster recovery facility, and this sometimes is one of the more difficult things to do). However, this choice does not include the word "downtime" and this choice is thus not as good as choice "B". Choice "a" is incorrect. Data input controls (and here the word does have meaning) have little to do with disaster recovery. Data input controls are an essential part of normal processing, and the normal controls would be available in the recovered applications once they are recovered. Downtime is addressed in this choice, but the inclusion of the data input controls makes this choice not as good as choice "B".Choice "c" is incorrect. This answer is a distractor.