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: Manama, Bahrain (CNN) -- Clashes broke out in Bahrain on Friday as authorities tried to prevent thousands of opposition supporters converging on a mosque to hear a sermon from the kingdom's most prominent Shia cleric, Sheikh Isa Qassim. The unrest followed a series of bombings in the capital, Manama, earlier this week, and the government's decision to strip some 31 opposition activists of their citizenship. Amid the unrest Friday, a teenage boy was knocked over by a car and killed as he crossed a busy road in the area. Sixteen-year-old Ali Abbas Radhi had been detained by police, according to witnesses and his family, and then escaped. They said he was hit by the car as he was pursued.Prominent Shia cleric Qassim delivered sermonPolice reportedly seal off access to mosqueTeen boy struck by vehicle during unrest and killed 
 Question:Earlier this week, authorities said the 31 people stripped of their _ nationality had harmed state security.

Bahrain