TASK DEFINITION: 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.
PROBLEM: Fact 1: Echinoderms use pheromones to communicate with each other. 
Fact 2: Echinoderms are represented by the starfish.

SOLUTION: Starfish use pheromones to communicate with each other.

PROBLEM: Fact 1: Plants release oxygen during the day but not during the night. 
Fact 2: Plants include blue pine, hemlock, spruce and oak.

SOLUTION: Blue pine releases oxygen during the day but not during the night.

PROBLEM: Fact 1: sonar is used to find the location of an object. 
Fact 2: Surface ships use sonar to locate and track submarines.

SOLUTION:
Ships use sonar to find submarines.