The correct answer is B. The default script field when adding an application specifies the script that will be executed if there are any problems running the configured script for the application. For example, if the configured script is missing, corrupted, or containserrors, the default script will be executed instead. The default script field is mandatory and must point to a valid script file1.

The other options are not correct because:

A. When a caller does not enter a choice in a Menu step, it will execute the default script. This is false because the Menu step has its own Timeout branch that determines what to do when the caller does not enter a choice within the specified timeout period. The default script field has no effect on the Menu step2.

C. When the caller enters a digit in the Menu step that is not defined, the default script will be executed. This is false because the Menu step has its own Unsuccessful branch that determines what to do when the caller enters a digit that is not defined as a valid option. The default script field has no effect on the Menu step2.

D. When the caller enters a digit that is not checked in the filter of the Get Digit String step, the default script will be executed. This is false because the Get Digit String step has its own Invalid Entry branch that determines what to do when the caller enters a digit that is not checked in the filter. The default script field has no effect on the Get Digit String step3.

References: 1: Cisco Unified Contact Center Express Administration Guide, Release 12.5(1) - Cisco Applications Configuration [Cisco Unified Contact Center Express] - Cisco 2: Cisco Unified Contact Center Express Editor Step Reference Guide, Release 12.5(1) - Chapter 2: Media Steps [Cisco Unified Contact Center Express] - Cisco 3: Cisco Unified Contact Center Express Editor Step Reference Guide, Release 12.5(1) - Chapter 3: Input Steps [Cisco Unified Contact Center Express] - Cisco