Boko Haram is an Islamic extremist group based in:

Boko Haram is a notorious Islamic extremist group that has caused immense devastation and instability in West Africa. The group is primarily based in North Eastern Nigeria. Officially known as Jamā'at Ahl as-Sunnah lid-Da'wah wa'l-Jihād, Boko Haram launched its insurgency in 2009 with the aim of establishing an Islamic state governed by Sharia law. Its activities, including kidnappings, bombings, and massacres, have also spread to neighboring countries like Chad, Niger, and Cameroon, making it a significant regional threat.

• Syria is associated with other prominent extremist groups like ISIS (Islamic State of Iraq and Syria), not Boko Haram.
• Thailand faces its own distinct insurgencies, particularly in its southern provinces, which are unrelated to Boko Haram.
• Therefore, 'None of these' is incorrect, as North Eastern Nigeria is the established base of the group.