CTFL_SYLL_4.0 Question #188: Real Exam Question with Answer & Explanation

An anti-intrusion system is battery powered and is activated by pressing the only available button. To deactivate the system, the operator must enter a PIN code. The system will stay in alert mode within a configurable timeout and an alarm bell will ring if the system is not deactivated before the timeout expires. The following state transition diagram describes the behavior of the system: What is the minimum number of test cases needed to cover every unique sequence of exactly 4 states/3 transitions starting and ending in the "Inactive" state? (note that "Inactive" is not a final state in the diagram)