Final answer:
Luanda is the most populous city and the capital of Angola, playing a key role in the country's economy and trade.
Step-by-step explanation:
The most populous city in Angola, which is also its capital city, is Luanda. Located on the narrow coastal plain of the country, Luanda is not just the administrative center but is also a significant port city that plays a crucial role in the nation's economy, particularly due to its proximity to oil-producing regions and the historical im portance of oil exportation to nations such as China.
The city's strategic position on the Atlantic coast has been vital for trade and the economic growth of Angola, despite the country facing issues associated with poverty in resource-rich regions.