Concept: The 1950 conference that discussed the Macpherson Constitution was hosted in Nigeria.Explanation:The Macpherson Constitution was named after Sir John Macpherson, the Governor of Nigeria at the time.In 1950, a conference was called to review and discuss the provisions of this constitution.The conference took place in Ibadan, bringing together representatives from different parts of the country.Their recommendations were used to shape the final constitutional arrangements.Answer: B. Ibadan