Which sentence correctly links the bridge to the relative clause without a second subject pronoun?
The bridge which it crosses the marsh is closed.
The bridge that it crosses the marsh is closed.
The bridge that crosses the marsh is closed.✓Respuesta correcta
The bridge who crosses the marsh is closed.
Explicación
That is the subject of crosses in the relative clause and refers to the bridge. The version with it is the closest distractor because the personal pronoun duplicates the subject already supplied by that.