What language did Dahl have to learn in order to live and work in Dar es Salaam?

Roald Dahl had to learn Swahili to effectively communicate and integrate into the culture while living and working in Dar es Salaam, Tanzania. As a British citizen stationed in East Africa during a time when many locals spoke Swahili, mastering this language was essential for both personal interactions and professional duties. Swahili served as a lingua franca in the region, allowing Dahl to build relationships with the local population and facilitate his work. The other languages listed, while they may have had some presence in the region, were not as pivotal for Dahl's day-to-day life and activities in Dar es Salaam as Swahili was.