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Verbal·Standard English Conventions·Boundaries
hard
Physical barriers, chemical defenses, and protein defenses are the three main categories of plant defense mechanisms. The alfalfa plant uses a __________ the plants produce proteins that are toxic to certain herbivorous insects.
Which choice completes the text so that it conforms to the conventions of Standard English?
A
protein defense
B
protein defense,
C
protein defense:
D
protein defense and