1821
a b - 1 bomber dropped four 2 , 000 - pound bombs on a building in a residential area of baghdad after getting intelligence reports senior officials were meeting there , possibly including saddam hussein and his sons .
 ( attack: dropped,  building: target, bomber: instrument, bombs: instrument) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: declare bankruptcy, transfer ownership, transfer money, marry, transport, die, phone write, arrest jail, convict, sentence, sue, end organization, start organization, end position, start position, meet, elect, attack, injure, born, fine, release parole, charge indict, extradite, trial hearing, demonstrate, divorce, nominate, appeal, pardon, execute, acquit, merge organization, Arguments type: beneficiary, prosecutor, plaintiff, seller, victim, buyer, agent, destination, artifact, organization, recipient, person, place, origin, target, giver, adjudicator, attacker, vehicle, defendant, entity, instrument. 
Text: {0} 
Answer:
 ( attack: dropped,  building: target, bomber: instrument, bombs: instrument) 