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.

[EX Q]: Fact 1: crossing two living things with recessive traits causes their offspring to have that recessive trait. 
Fact 2: Mutations cause various differences between the offspring and their parents.
[EX A]: recessive traits causes Mutations.

[EX Q]: Fact 1: Echinoderms use pheromones to communicate with each other. 
Fact 2: Echinoderms are represented by the starfish.
[EX A]: Starfish use pheromones to communicate with each other.

[EX Q]: Fact 1: volcanic ash in the atmosphere decreases the temperature by blocking the sun. 
Fact 2: Ash clouds are a particular problem for aircraft.
[EX A]:
Volcanic clouds in the atmosphere is a particular problem for aircraft.