Nhận biết (M1)

Plants often reduce photosynthesis in undamaged parts of their leaves when other parts are being eaten by insects. It appears that feeding triggers the closure of stomata-tiny openings that allow carbon dioxide to enter the leaf-thereby limiting plants' ability to fix carbon (capture and convert it to carbohydrates during photosynthesis). In a study of genetically identical plants, those that were modified to emit an insect-deterring chemical compound experienced a smaller decline in photosynthesis under insect attack than those that did not emit the compound. Since the two types of plants showed no other differences, this finding suggests that __________

Which choice most logically completes the text?

• A.

  emitting the defensive compound enabled plants to keep their stomata open to a greater extent than they otherwise would have.

• B.

  plants that emitted the defensive compound converted a greater proportion of captured carbon to carbohydrates than they otherwise would have.

• C.

  emitting the defensive compound allowed plants to compensate for stomata closure by fixing carbon more efficiently.

• D.

  there may have been underlying genetic differences between the plants that strengthened the correlation between compound emission and photosynthesis efficiency.