下列物质的名称和化学式相符的是（　　）

A．氯化铁（FeCl₂）

B．硫酸钠（Na₂SO₄）

C．氯化银（AgCl₂）

D．氢氧化镁（MgOH）

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

A．of whom

B．of which

C．about that

D．about whom