A species of spruce tree occupies the same niche at the mouth of a river that a species of pine tree occupies further upstream. One year, several pinecones fall into the river and are carried to the mouth, where they take root and grow amongst the spruce trees. What will be the most likely result of this occurrence

The correct option is: "Either the pine trees or the spruce trees will eventually evolve into a new species."

Explanation:

There will be a competition between spruce trees and pine trees for nutrition and other resources from the environment to grow and spread since they are now occupying the same niche. Overtime, one specie will outlive the other by evolving into a specie that gives it an advantage over the other.  

digestion

it excretes wastes