Answer:
Since I can not see the map.
but according to my knowledge option B is correct.
Step-by-step explanation:
As I studied population is most concentrated along the Nile river. River Nile is the longest river of the world and is in existence since the Stone Age.
It had played crucial role in the founding of Egyptian civilization and since past population flourished along the river and also spreading in the current world. It is an international river which originates in Burundi and then passes through number of African countries such as Rwanda, Eritrea, Congo, Kenya, Tanzania, Ethiopia, Sudan, Egypt and many others. Several cities had flourished and are flourishing along the river and has become the major source for agriculture, trading, etc. and hence is the lifeline of millions of population.