Step by Step Explanation: * A: Randomizing the keypad reduces the risk of shoulder-surfing attacks by eliminating predictable patterns. * C: Randomization increases the cognitive load on users, making it harder to input numbers quickly. * D: Additional computational power is minimal and not typically a trade-off. * E and F: Remembering access numbers or weak passwords are unrelated to keypad randomization. Reference: CASP+ Exam Objectives 3.4 - Evaluate usability and security trade-offs in design.