Gravity
Plant roots always grow downward because specialized cells in root caps detect and respond to gravity. This is an example of a tropism. A tropism is a turning toward or away from a stimulus in the environment. Growing toward gravity is called geotropism.
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Roots B.
Stem C.
Xylem D.
Phloem
The pathway that the viruses would most likely follow on first entering the plant is D. PHLOEM.
The phloem, whose purpose is to transport food from the leaves to the plant, is used as the pathway to spread the virus throughout the plant. The manifestation of aphid transmitted virus is the yellowing, mottling, or curling of leaves and the stunted growth of the plant.
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