SAT Question 7f1df833: Form Structure And Sense answer and explanation

English - Form Structure And Sense - Finite And Nonfinite Verb Forms
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In 1966, Emmett Ashford became the first African American to umpire a Major League Baseball game. His energetic gestures announcing when a player had struck out and his habit of barreling after a hit ball to see if it would land out of ______ transform the traditionally solemn umpire role into a dynamic one.
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Difficulty:Medium
Which choice completes the text so that it conforms to the conventions of Standard English?