Concept:The most notable policy of the Buhari military regime was a national moral reorientation campaign.
Explanation:The Buhari regime introduced the War Against Indiscipline in 1984.
Its purpose was to correct social misconduct, corruption, and lack of order in Nigeria.
Option A is not linked to this regime.
Option B is associated with the Shagari civilian administration.
Option D, the Structural Adjustment Programme, was introduced by the Babangida regime.
Therefore, the regime's most remarkable achievement was the War Against Indiscipline.
Answer:C. War Against Indiscipline