The correct option for the military Head of State during the Third Republic in Nigeria is C. General Murtala Muhammed. Detailed Explanation:

1. Understanding the Context:
2. The Third Republic in Nigeria refers to the period from 1993 to 1994, which was characterized by a brief attempt at democratic governance after years of military rule. However, the military rule that preceded this period is crucial to understanding the leadership transitions.
3. Identifying the Military Heads of State:
4. General Olusegun Obasanjo: He was the military Head of State from 1976 to 1979, during the Second Republic. He later became a civilian president after the military handed over power.
5. General Ibrahim Babangida: He was the military Head of State from 1985 to 1993. His regime was marked by significant political changes, including the transition to a Third Republic, but he was not the Head of State during the actual Third Republic.
6. General Murtala Muhammed: He was the military Head of State from 1975 until his assassination in 1976. His leadership was part of the Second Republic, not the Third.
7. General Sani Abacha: He ruled from 1993 until his death in 1998, but he was not the Head of State during the Third Republic, as he came to power after the military coup that ended the brief democratic experiment.
8. Why the Other Options are Incorrect:
9. A. General Olusegun Obasanjo: Incorrect because he was not in power during the Third Republic; he was a military leader in the 1970s.
10. B. General Ibrahim Babangida: While he was a significant military leader, he was in power until 1993, and the Third Republic began after his regime ended. Therefore, he cannot be considered the military Head of State during the Third Republic.
11. C. General Murtala Muhammed: Incorrect for the same reason as above; he was a military leader before the Third Republic.
12. D. General Sani Abacha: He ruled after the Third Republic had been established and was known for his authoritarian regime, which followed the brief democratic period.

Summary of Key Points:

• The Third Republic in Nigeria was a short-lived democratic period from 1993 to 1994.
• General Murtala Muhammed was a military leader but not during the Third Republic; he was part of the Second Republic.
• General Ibrahim Babangida was the military leader before the Third Republic but not during it.
• General Sani Abacha ruled after the Third Republic and was known for his military dictatorship.

Revision Summary:

• The Third Republic in Nigeria lasted from 1993 to 1994.
• General Murtala Muhammed was not the military Head of State during this period.
• General Ibrahim Babangida was the military leader before the Third Republic.
• General Sani Abacha ruled after the Third Republic ended.

In conclusion, the correct answer to the question regarding the military Head of State during the Third Republic is C. General Murtala Muhammed.