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.

Fact 1: Behaviors that improve fitness increase through natural selection. 
Fact 2: Darwinism is strictly, selection theory.
behaviors that improve fitness increase through Darwinism.

Fact 1: detailed observation of celestial objects requires a telescope. 
Fact 2: All telescopes collect light and magnify it .
Detailed observation of celestial objects requires the collecting of light and magnifying it.

Fact 1: Most plants continue to grow throughout their lives. 
Fact 2: Fertilizers help plants grow.

Most plants cultivate their entire lives and Fertilizer helps them.