Why Lord sri krishna only said bhagvathgeetha to Arjuna??

  Why Lord sri krishna only said bhagvathgeetha to Arjuna and showed his viswaroopam to only Arjuna?? why he didnt say to remaining 4 pandavas as they are also good in character and follows dharma???

 Actually the lord tried twice to give the gyan of bhagavan geeta to others also, but those people did not give a chance or allow krishna to continue and syopped him from giving them the gyan...... do who these peoplevare? Its Duruodhan, actually lord tried yo give him that gyan during shanti prastav, but duryodhan was sooooo head strong that he did not try to listen but instead tried to make krishna his captive, thus duryodhan list his chance, the other person was karna....... krishnavtruedvto give him the gyan of bhagavad geeta when he met karna aftervshantinprastav and revealed him the secret of his birth and tried to persuade him to join the pandavas forces , at that time lord was very enthusiastic to give the gyan , but the adament karna stopped krishna by clearing his decision to stay with duryodhan and thus making krishna to stop, ginally, arjun's reluctance to fight the war led krishna to give the gyan to arjun, and arjun being the most benovalant, and havind submitted him self to krishna received the gyan.