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: being burried under soil and mud changes peat into coal through extreme heat and pressure in a swamp over a long period of time. 
Fact 2: Most coal is fossil peat.
answer:
fossils turn into coal over time.


question:
Fact 1: if an object is black then that object absorbs all visible light. 
Fact 2: Black objects absorb all different wavelengths of light.
answer:
If something is black then it absorbs all different wavelengths of light.


question:
Fact 1: the ovaries are used in reproduction. 
Fact 2: Unlike most female animals, which have two functioning ovaries, the chicken usually has only one.
answer:

Something chickens have only one that functions is used in reproduction.