There were 20 people sitting in the room, half ___ were women.

A．of whom

B．of which

C．about that

D．about whom

县级调查成果在经过自检、省级国土资源管理部门组织的预检和验收、国土资源部组织的遥感影像库与数据库一致性全面核查，当符合调查规程要求时，调查成果将被确认。该调查成果将作为______农村土地调查数据库建设的基础。

A．国家级
B．省级
C．市级
D．县级