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: Washington (CNN) Shortcomings at federal and state agencies allow sales of firearms to people prohibited from buying them, a Justice Department inspector general probe found. The issue became the subject of investigation after the FBI said the alleged shooter charged in the 2015 mass shooting at a South Carolina church should not have been able to buy a firearm. The FBI failed to complete the background check in the three days required by law, allowing the alleged shooter to buy the gun. While the FBI runs background checks, the Bureau of Alcohol Tobacco Firearms and Explosives is responsible for retrieving guns from buyers who weren't legally permitted to purchase them.The issue became the subject of investigation after last year's South Carolina church shootingFor the past 15 years, the FBI and ATF have disagreed over what is a "fugitive from justice" 
 Question:There were nearly 50,000 such purchases between 1999 and 2015 that the _ sought to deny, but that the ATF didn't agree required the agency to try to retrieve the gun.

FBI