A. black-box
B. white-box
C. grey-box
D. none of the mentioned
✅ The correct answer is option A.
Explanation: The system is considered as a black box whose internal details are not known that is, only its visible external (input/output) behavior is documented.
Explanation: The system is considered as a black box whose internal details are not known that is, only its visible external (input/output) behavior is documented.