Why should the each component be located at each datacenter?

Locating each component in every datacenter is a fundamental design principle for achieving site failover, ensuring business continuity if one site becomes unavailable, and increases security for remote access by providing localized, redundant access points. This distributed architecture minimizes a single point of failure and can improve the resilience of remote access services.

Distributing components across multiple datacenters typically increases, rather than reduces, design complexity due to the need for inter-site communication, synchronization, and failover mechanisms.

Having components in multiple datacenters generally adds to administration complexity, requiring coordination and management across different locations, rather than simplifying it.

While preventing user experience impact during a site outage is a benefit, choice A provides a more comprehensive explanation, including the critical aspect of 'site failover' which directly addresses outage impact, and adds the important point about 'increased security for remote access'.