Which statement best reflects the current understanding of pollen tube elongation?
a. It is not even known if pollen tube growth uses chemical signals or is completely random.
b. Pollen tube elongation will occur as long as the pistil provides moisture and energy.
c. While it is known that chemical cues from female tissues help guide pollen tube growth, the identity of these chemicals is not known.
d. Nearly all of the details of the chemical interactions between the pollen tube and pistil tissue are known.
Answer: c. While it is known that chemical cues from female tissues help guide pollen tube growth, the identity of these chemicals is not known.
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