The correct option is 1 only because the formation of the African and Eurasian desert belt is primarily influenced by the presence of sub-tropical high-pressure cells. These high-pressure systems lead to sinking air, which inhibits cloud formation and promotes dry conditions, creating arid environments characteristic of deserts. Conversely, while warm ocean currents can influence regional climates, they are not the main driver of desert formation; rather, it is the persistent high-pressure zones that establish the dry climate characteristic of these desert regions.