选B
因为：through 作介词时多指从中穿过,通过,walk through the forest,send the message through email；是从一头（边）贯穿到另一头（边）.例The river runs through our city.He passed through the hall.
across 是指在表面上掠过,穿过,如 walk across the bridge,fly across the moutain,
还有对面的意思,如across the road ,
与“道路”交叉形成“十字”,go across the street
因此,本题选B.
祝进步.