Final answer:
The Swahili language developed as a result of Muslim merchants traveling to the coast of east Africa for trade and needing a lingua franca to communicate with locals. Arab traders and Persian settlers intermingled with the Bantu people and created a unique blended language and culture known as Swahili.
Step-by-step explanation:
The word 'sawahili' means 'a language of the coast' in Arabic, which is related to the Swahili language spoken today in Kenya, Tanzania, and northern Mozambique. The development of Swahili can be explained by option a) Muslim merchants traveled to Africa and needed a way to communicate with people along the coastal areas of the Indian Ocean for trade, leading to the development of a lingua franca. Arab traders and Persian settlers intermingled with the Bantu people on the east African coast, resulting in a unique blended language and culture known as Swahili. Swahili served as the main language of trade and communication for people from different ethnic groups in the coastal cities.