Mark the only option in which the word(s) in bold type...

"but controllers also must direct planes efficiently…" (line 6 ).

"In addition, controllers keep pilots informed about changes in weather conditions…" (lines 17-18).

"...such as wind shear, a sudden change in the velocity or direction of the wind…" (lines 18-20).

"If the path is clear, the controller directs the pilot to a runway;" (lines 27-28).

"As the plane nears the runway, the pilot is asked to contact the tower." (lines 30-31).