Im possibly thinking of the answer C...
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The research revealed that cats, on average, sleep 50% more in a 24-hour period than dogs.
The answer is A.
B makes no sense, and is incorrect.
C, is alright, but not the best.
Analyzing the sentence, theonly adverb is <em>frequently; </em>this is an adverb of frequency, because it tells how often an activity is conducted. Regarding the other components of this sentence, Sandy cheeks seems to be the name of the person, eats carrots the verb and its complement, to improve is an infinitive of purpose, her is the possessive adjective and eyesight a noun.