Concept:Conakry is the national capital of Guinea, a country in West Africa.
Explanation:First, identify the country that Conakry belongs to.
Conakry is a major seaport on the Atlantic coast of West Africa.
It serves as the seat of government of the Republic of Guinea.
Now check each option given.
Algiers is the capital of Algeria, not of Guinea, so option A is incorrect.
Antananarivo is the capital of Madagascar, so option C is incorrect.
Johannesburg is a major city in South Africa, but it is not a national capital, so option D is incorrect.
Option B directly names Guinea as the correct country.
Therefore, Conakry is the capital of Guinea.
Answer:B. Guinea