---What is _________attract you most when you paid a visit to Beijing the other day?

--- The beautiful scenery and being warmly welcomed by the people.

A．it which

B．that that

C．it that

D．that which

下列关于白细胞的功能的说法，正确的是 [ ]

A．运输养料和废物

B．运输氧气和一部分二氧化碳

C．加速止血和凝血

D．具有保护和防御功能