Question

Read the passage below carefully:

Across the Sahelian belt of West Africa, traditional earthen architecture is undergoing a critical re-evaluation by modern urban planners. For decades, Western-style concrete structures dominated municipal development, despite their tendency to trap radiant heat and drastically increase indoor temperatures. Earthen buildings—constructed using locally sourced clay, straw, and laterite—naturally regulate thermal mass, absorbing daytime heat and releasing it slowly during cooler desert nights. Additionally, thick clay walls and shaded internal courtyards significantly reduce the energy load required for mechanical ventilation. While critics once dismissed earth-based construction as primitive or short-lived, recent architectural trials in cities like Niamey and Ouagadougou demonstrate that refined soil-stabilization techniques render these structures both durable and rain-resistant. Beyond thermal efficiency, promoting earthen construction supports localized economies by decreasing reliance on expensive imported cement. Consequently, integrating indigenous building wisdom with contemporary engineering offers a viable, sustainable framework for combating extreme urban heat across the region.

Which of the following best expresses the main idea of the passage?