Final answer:
AER closely coordinates with FEMA, an agency responsible for assisting state and local governments during emergencies and key to homeland security.
Step-by-step explanation:
The organization that AER (presumably refers to an emergency response agency) closely coordinates with is the Federal Emergency Management Agency (FEMA). During times of natural disasters and emergencies, FEMA is tasked with assisting state and local governments, coordinating various agencies, and utilizing rescue infrastructure. The reference to the work done by the U.S. Coast Guard in rescuing over thirty-five thousand people hints at the importance of inter-agency collaboration. However, in the context of the Hurricane Katrina disaster, FEMA was criticized for its ineffectiveness and the lack of coordination. Despite these challenges, agencies like FEMA are crucial for federal disaster response and homeland security.