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: New York (CNN) Drug kingpin Joaquin "El Chapo" Guzman, a Houdini-like master of escape accused of running one of the world's largest drug trafficking organizations, entered a not guilty plea through his attorney at an arraignment Friday in federal court in Brooklyn. The diminutive, clean-shaven trafficker, described by a federal official as "the most notorious criminal of modern time," was not handcuffed and wore a dark blue short-sleeved shirt and pants with white sneakers during his brief appearance in a packed courtroom. Magistrate Judge James Orenstein asked Guzman whether he understood the charges, including the operation of a continuing criminal enterprise, conspiring to murder rivals, firearms violations and money laundering.Joaquin "El Chapo" Guzman makes first US court appearance with Friday arraignmentUS authorities said they didn't know Mexican cartel leader would be extradited ThursdayGuzman taken into US custody on eve of Donald Trump's inauguration 
 Question:"This extradition would not have been possible without the strong efficient close cooperation we have in our working relationship with our _ counterparts," he said.

Mexican