Which sentence uses the underlined vocabulary word
incorrectly?
A. The gold glinted duly in the shadowy
light.
B. The imminent danger of swimming with
sharks didn't keep the researchers out of
the water.
C. The spelling bee contender flashed a
self-possessed smile as the final word was
announced

C. The spelling bee contender flashed a  self-possessed smile as the final word was announced.

Explanation:

You have not pointed out which words are underlined, but either way, we can see that sentence C is the only one that contains a word that is used incorrectly. This word is self-possessed. A smile can't be self-possessed. This adjective is used to describe a person - someone who is self-possessed is calm, confident, and in control of their emotions.  

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