n what part of China did the population increase the most? the northeast the northwest the southeast the southwest

Exceptionally high population densities occur in the Yangtze delta, the Pearl River Delta, and on the Chengdu Plain of the western Sichuan Basin. Most of the high-density areas are coterminous with the alluvial plains on which intensive agriculture is centred.

Well all those are true except one that would be that a ballad often features a refrain.