A landlocked country is a country that is completely surrounded by land and has no direct access to the sea or ocean. China and South Africa are not landlocked countries as they have coastlines along the sea. Tunisia is not a landlocked country as it has a coastline along the Mediterranean Sea.
Therefore, the answer is Burundi, which is a landlocked country located in East Africa. It is surrounded by Tanzania to the east and south, the Democratic Republic of the Congo to the west, and Rwanda to the north. Being landlocked can have economic implications for a country as it can limit trade and access to international markets.