Concept:The Efik are an ethnic group whose homeland lies in the southern part of Cross River State, Nigeria.
Explanation:The Efik belong to the larger Ibibio ethnic family in Nigeria.
They are found mainly in the coastal and riverine areas of Cross River State.
Cross River State is located in the South-South geopolitical zone of Nigeria.
The South-South zone forms part of the broad region known as Southern Nigeria.
Northern Nigeria is too far away, so option A is not correct.
Western Nigeria is also far from Cross River State, so option D is not correct.
Eastern Nigeria is an older regional term and is less precise for the modern location.
Therefore, the Efik are best described as being primarily located in Southern Nigeria.
Answer:C. Southern Nigeria