निम्नलिखित में से किसने विकास के रैखिक चरणों के सिद्धांत पर आधारित आर्थिक विकास का मॉडल प्रस्तावित किया था?

In traditional anthropological classification of human races, which racial group was characterized as 'yellow-skinned'?

What is the approximate estimated proportion of ecumene (habitable) and non-ecumene (uninhabitable/sparsely inhabited) areas on the Earth's surface?