The complete question is :
The success of plants extending their range northward following glacial retreat is best determined by _____.
A) whether there is simultaneous migration of herbivores
B) their tolerance to shade
C) their seed dispersal rate
D) their size
Answer: The seed dispersal rate
Explanation:
The seed dispersal can be defined as the movement of the seeds away from the parent plant. The ability of the plant to extend is completely dependent on the ability of the plant to disperse its seeds.
Plants have very limited ability, they need vectors to carry its seed from one place to another.
The biotic and abiotic vector both are involved in carrying the seeds which helps in expansion of the trees.
hence, the correct answer is option C
<span>D. Vascular tissue
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Vascular tissue is responsible for transporting water and nutrients in plants. <span> The Vascular tissue consists of the Xylem and the Phloem. The main function of the Xylem is to transport water and minerals throughout all parts of the plant. Phloem on the other hand is responsible for transporting organic molecules that are larger in size. The vascular system, consisting on the Xylem and the Phloem runs from the roots of the plats through the branches and upto the leaves. It controls the total transportation of the water and nutrients.</span>
3rd Choice. It describes a processed known as crossing over which results in genetically distinct daughter cells.