instruction:
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.
question:
Fact 1: dehydrating food is used for preserving food. 
Fact 2: Dehydration is the removal of water.
answer:
Removing water preserves food.


question:
Fact 1: rocks interacting with wind over long periods of time causes weathering. 
Fact 2: Rocks weather at different rates.
answer:
wind affects rocks.


question:
Fact 1: an egg requires warmth to survive. 
Fact 2: And humans do come from eggs, eggs without shells, they are called ovum.
answer:

Some ovum require warmth to survive.