Option 1: Although some of these countries may have mineral resources, the assertion that all of them have recent discoveries of rich deposits of rare earth elements is not accurate.

Option 2: There`s no record of the Chinese establishing military bases across all these countries recently. China`s military presence is generally more concentrated in the South China Sea.

Option 3: While true that the Sahara Desert is expanding, this phenomenon is not the primary reason these four countries made international headlines recently.

Option 4: This is the correct answer. Chad, Guinea, Mali and Sudan have all suffered political instability in recent years culminating in successful coups. These events made the international community concerned about the instability in these countries and the potential impacts on their citizens and the surrounding regions. Therefore, these countries have been in the spotlight due to the successful coups rather than any other reasons provided in the options.