Concept:The official Biafran leader who formally ended the secessionist state by surrender in 1970.
Explanation:The Nigerian Civil War lasted from July 1967 to January 1970.
When Chukwuemeka Odumegwu Ojukwu left Biafra, Major General Philip Effiong assumed leadership.
Effiong had served as the Chief of Defence Staff of the Republic of Biafra.
On January 15, 1970, he formally surrendered and renounced the existence of Biafra.
He made this declaration to the Nigerian federal government led by General Yakubu Gowon.
Answer:C. Major General Philip Effiong