Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.
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Question: Fact 1: Light enters the eye through an opening called the pupil. 
Fact 2: Light is essential to vision.

Answer: vision requires the pupil.


Question: Fact 1: competition may cause animals to fight towards members of their own species. 
Fact 2: Mock fights also teach animals to interact with others of their species.

Answer: Competition may cause animals to interact with other animals of their species.


Question: Fact 1: erosion causes a river to become deeper and wider. 
Fact 2: Water erosion has similar consequences as wind erosion.

Answer:
The power of wind and water can cause a river to deepen and widen.