Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: (CNN) -- A bill that requires cruise ships to tighten security measures and report alleged crimes is awaiting President Obama's approval. The Senate on Wednesday passed the Cruise Vessel Security and Safety Act, after it received broad bipartisan support in the House with a vote of 416-4 last year. Peepholes on cabin doors, rails no lower than 42 inches and information packets on how to report crimes are some of the changes commercial cruise passengers can expect to see after the legislation takes effect. Ships built after the legislation's passage also must be equipped with security latched and time-sensitive key technology.Cruise Vessel Security and Safety Act calls for peepholes on cabin doors, higher ship railsShips must carry rape kits, STD medications, medical staff to treat sex assault victimsBill also requires cruise ships to quickly report incidents to FBI, keep detailed logsLegislation applies to all commercial cruise ships that dock in United States 
 Question:Vessels also must keep a log of incidents and contact the nearest FBI field office "as soon as possible" after a homicide, kidnapping, assault or disappearance of a _ national is reported.

United States