Take context from the input text and decide on the accurate relationship between 'Boko Haram' and 'Abubakar Shekau' from the options provided.
Options: creator, distribution format, chairperson, legal form

Leader of the Boko Haram sect, Abubakar Shekau has again resurfaced in a recording and denied claims by Chadian … see more » Copyright © 2015 Vanguard.
chairperson