In the recent years Chad, Guinea, Mali and Sudan caught the international attention for which one of the following reasons common to all of them?

The correct option is (d) because Chad, Guinea, Mali, and Sudan all experienced successful military coups or unconstitutional changes of government between 2020 and 2023, leading to significant regional instability. While option (c) regarding the southward expansion of the Sahara is a long-term environmental reality for these Sahelian countries, it was the sudden political upheavals and military takeovers that captured specific international headlines during this period. The core concept being tested is contemporary geopolitical shifts and the crisis of democratic governance in the African continent.