下列经济活动最早见于南北朝时期的是

①用水排鼓风冶铁 ②用灌钢法炼钢

③到乡村赶草市   ④在省城住会馆

A．①②

B．①④

C．②③

D．③④

Conditions necessary for the development of a positive sense of self-esteem include

A．consistent limits.

B．critical environment.

C．inconsistent boundaries.

D．physical discipline.