Final answer:
Great Britain and France (option 4) were responsible for partitioning Southwest Asia after the Ottoman Empire's breakup, dividing the region into mandated territories without regard for the diverse ethnic and nationalist aspirations of its inhabitants.
Step-by-step explanation:
The two European countries responsible for the partitioning of Southwest Asia after the breakup of the Ottoman Empire were Great Britain and France. These two colonial powers entered into agreements, such as the 1916 Sykes-Picot Agreement, to divide the Middle Eastern territories into spheres of influence, based primarily on their strategic and economic interests, particularly in relation to oil resources. The division of the region was formalized under the post-World War I mandates of the League of Nations, with Great Britain and France taking control of future Iraq, Israel, Jordan, Lebanon, and Syria, among other areas, regardless of the local populations' preference for self-determination.