|Question 2Verbal

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Even among fast animals, top speeds can vary significantly. For example, the quarter horse can run up to 89 kilometers per hour (km/hr), whereas the white-throated needletail swift is much faster, flying up to 169 km/hr. This difference is largely because the features that are        for running on land restrict top speeds more than the features needed for flying through the air.
Which choice completes the text with the most logical and precise word or phrase?
trivial
A
essential
B
challenging
C
approved
D