In the coastal regions of Florida, Avicennia germinans and Avicennia marina-two plants in the Acanthaceae family commonly known as the black and gray mangrove-grow in salinated, oxygen-poor sections of swampy mudfats. Botanists Karine Lefebvre and Noelle Alphonse described how A. germinans and A.marina, which have shallow below ground roots, have additional small roots that extend vertically out of the water; more detailed examination revealed that these roots have passages that open up. The researchers theorize that the plants rely on taking in oxygen through these passages, as their structure not only allows the plant to draw in the oxygen but also enables it to be transported to the plant's living tissues. Which finding, if true, would most directly support the researchers' theory? A higher oxygen content but have vertical roots similar to those of A. Other species in the Acanthaceae family are found in waters with germinans and A. marina. B passages, the relative lengths of the vertical roots differ greatly Although both A.germinans and A. marina have vertical roots with B between the two species. C lower oxygen content have more vertical roots extending up out of A. germinans and A.marina plants that are growing in waters with the water. D deeper waters where the vertical roots do not extend into the air. A. germinans and A.marina grow well even when transplanted to

The researchers' theory is that A. germinans and A. marina rely on taking in oxygen through the passages in their vertical roots, which allows the oxygen to be transported to the plant's living tissues. The finding that would most directly support this theory would be one that shows a correlation between the presence of vertical roots with passages and the ability of the plants to survive in low-oxygen environments.<br /><br />Option C states that "A. germinans and A. marina plants that are growing in waters with lower oxygen content have more vertical roots extending up out of the water." This finding would directly support the researchers' theory, as it suggests that the plants with more vertical roots are better able to take in oxygen and transport it to their living tissues in low-oxygen environments.<br /><br />The other options do not directly support the researchers' theory. Option A does not provide any information about the relationship between vertical roots and oxygen content. Option B suggests that the relative lengths of the vertical roots differ between the two species, but this does not provide any information about the relationship between vertical roots and oxygen content. Option D suggests that A. germinans and A. marina grow well even when transplanted to deeper waters where the vertical roots do not extend into the air, but this does not provide any information about the relationship between vertical roots and oxygen content.