In which year were two additional DACs certified by TSA?

The year 2012 is significant because it marked the certification of two additional Designated Aviation Channels (DACs) by the Transportation Security Administration (TSA). This event is important in the context of enhancing security measures and ensuring that certain aviation-related entities meet specific regulatory standards. The certification indicates that these channels have passed TSA's rigorous evaluation processes, allowing them to be recognized as reliable and secure pathways for aviation operations.

The years mentioned in the other options do not correspond to the event of certification of additional DACs, illustrating the specific timeline of TSA's oversight and regulatory actions in relation to aviation security.