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
