Correct Answer: CIn Citrix environments, a Unified Gateway (option C) provides users with a single URL for logon and ensures seamless single sign-on to both the NetScaler Gateway virtual server and web applications being load-balanced by the NetScaler. Global Server Load Balancing (GSLB) is used for load balancing requests across multiple data centers and does not inherently provide single sign-on capabilities. AAA (Authentication, Authorization, and Accounting) virtual servers handle authentication separately rather than providing a unified gateway. Load Balancing virtual servers specifically manage distribution of network or application traffic but do not offer single sign-on features. Therefore, the correct choice for achieving single sign-on with a single URL is a Unified Gateway.