You will be given a definition of a task first, then some input of the task.
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].

Calexico, California (CNN) For the first time on the border, drug traffickers allegedly bought U.S. property for the sole purpose of building a house to conceal the end of a 415-yard smuggling tunnel from Mexico, authorities said Wednesday. Inside the life of a drug-trafficking teen Four people were arrested this week in connection with a raid on the tunnel underneath a three-bedroom house in Calexico, California, that sits about 300 yards north of the international line, authorities said. The tunnel entrance was inside a restaurant in Mexicali, Mexico, according to U.S. Immigration and Customs Enforcement. Authorities confiscated 1,532 pounds of marijuana, with a street value of nearly $6 million.Smugglers allegedly bought U.S. property for the sole purpose of hiding a drug tunnel, feds saySmugglers allegedly built a house with a hole in living room that led to tunnelThe drug tunnel ran 415 yards between Calexico, California and a restaurant in Mexicali, Mexico 
 Question:Smugglers also used a second _ residence four miles from the tunnel exit to store the drugs and then they moved the narcotics to a Calexico warehouse, where transportation cells moved the drugs to the cities northward, authorities said.
Output:
Calexico