Which one of the following is the MOST important in designing a biometric access system...

The most important factor in designing a biometric access system if it is essential that no one other than authorized individuals are admitted is the False Acceptance Rate (FAR). FAR is the probability that a biometric system will incorrectly accept an unauthorized user or reject an authorized user2. FAR is a measure of the security or accuracy of the biometric system, and it should be as low as possible to prevent unauthorized access. False Rejection Rate (FRR), Crossover Error Rate (CER), and Rejection Error Rate are not as important as FAR, as they are related to the usability or convenience of the biometric system, rather than the security. FRR is the probability that a biometric system will incorrectly reject an authorized user or accept an unauthorized user. CER is the point where FAR and FRR are equal, and it is used to compare the performance of different biometric systems. Rejection Error Rate is the probability that a biometric system will fail to capture or process a biometric sample. References: 2: CISSP For Dummies, 7th Edition, Chapter 4, page 95.