|Question 20Verbal

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If an animal can recognize itself in a reflective surface (“the mirror test”), it is considered to have self-awareness. In a recent study, scientists _______ for evidence of self-awareness in snakes, species that rely primarily on olfactory rather than visual processing, adapted the test to foreground smell, modifying the scent trails of North American eastern garter snakes and African ball pythons.
Which choice completes the text so that it conforms to the conventions of Standard English?
searched
A
were searching
B
have searched
C
searching
D