According to the Cisco Packaged Contact Center Enterprise Features Guide, Release 12.0 (1), a Post Call Survey is triggered by the hang-up event from the last agent1. When the agent hangs up, the call routing script launches a survey script. The value of the expanded call variable user.microapp.isPostCallSurvey controls whether the call is transferred to the Post Call Survey number. If user.microapp.isPostCallSurvey is set to y (the implied default), the call is transferred to the mapped post call survey number. If user.microapp.isPostCallSurvey is set to n, the call ends1. Therefore, to invoke the Post Call Survey successfully, the routing script logic should direct the call to the Post Call Survey dialed number after the agent disconnects from the caller. The other options are not correct, because they either do not involve an agent interaction or do not set the user.microapp.isPostCallSurvey variable correctly.
Reference:
1: Cisco Packaged Contact Center Enterprise Features Guide, Release 12.0 (1) - Post Call Survey