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: The radicalised Muslim 15-year-old who shot a police accountant in an 'act of terrorism' had heard a lecture by an extremist group just hours before storming the force headquarters. Farhad Jabar Khalil Mohammad reportedly listened to a talk by hardline Islamist group Hizb ut-Tahrir at Parramatta mosque where he changed into a black robe before killing Curtis Cheng, according to Seven News. He walked towards the nearby police station on Friday afternoon, stopping at his school en route to dump his backpack which contained material linked to a Sydney Islamic bookstore. The Iranian-born youth then concealed his gun in his clothing and headed towards NSW Police headquarters in Parramatta, Sydney, where he shot Mr Cheng in the back of the head.Farhad Jabar Khalil Mohammad stormed police headquarters in ParramattaHe reportedly heard lecture by extremist group Hizb ut-Tahrir before killingSchoolboy, 15, changed into a black robe before shooting accountantHe also stashed a bag containing material linked to Islamic bookstore 
 Question:A senior Hizb ut-_ figure is believed to have given a lecture on the day of the shooting, but leaders of the group have refused to condemn the attack.

Tahrir