What can a Citrix Administrator use to restrict access to the Citrix ADC management IP...

Correct Answer: B. Access Control List (ACL)

Short Explanation with reference:

An Access Control List (ACL) is a set of rules that can be used to allow or deny traffic to or from the Citrix ADC appliance1. A Citrix Administrator can use ACLs to restrict access to the NSIP address, which is the IP address used for management purposes2. By default, secure access to the NSIP address is enabled, but it can be disabled by using the -gui option in the CLI or by unchecking the Secure Access only check-box in the GUI2. Alternatively, a Citrix Administrator can also use the allowedManagementInterface parameter to define the list of permitted management interfaces for system users3.

1: Configuring ACLs | NetScaler 2: How to Enable Secure Access to Citrix ADC GUI Using the SNIP/MIP Address of the Appliance 3: Restricted system user authentication to NetScaler management interfaces