Concept:The first executive president is the first leader to hold real executive powers under Nigeria's presidential system of government.Explanation:Nigeria adopted an executive presidential system during the Second Republic.Shehu Shagari won the presidential election and was sworn in as the first executive president of Nigeria.He took over power from the military regime led by Olusegun Obasanjo.Earlier leaders, such as Nnamdi Azikiwe, served under a parliamentary system and were not executive presidents.Therefore, Shehu Shagari is generally recognized as the first executive president.Answer:B. Shehu Shagari