The correct answer is D.
The Swahili language does in fact blend aspects of Bantu with Arabic. Swahili is a Bantu language (a family of languages spoken throughout Sub-Saharan Africa) that have received a strong influence from Arabic, due to the contact with Arabs and to the fact that many Swahili speakers have been Muslims for many centuries. This proximity with Arabic is logical since Swahili is spoken in the Eastern coast of Africa, very near to the Arabic speaking communities of the Horn of Africa and the Arabian Peninsula. That is why this is an example of how the proximity to the coast affected the culture of East Africa.
