ग्लोब पर किस अक्षांश विस्तार में विश्व की सर्वाधिक जनसंख्या का संकेंद्रण पाया जाता है?

A large portion of the non-ecumene region of the Earth has remained sparsely populated primarily because of:

A significantly low sex ratio (fewer females per male) is most typically associated with which type of urban centers due to male-selective migration?