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: Constriction occurs when the muscular walls of blood vessels contract. 
Fact 2: Dehydration causes vessels to constrict and blood to thicken.

SOLUTION: Constriction causes blood to thicken.

PROBLEM: Fact 1: Pressure receptors are found mainly in the skin. 
Fact 2: Skin is the body's largest organ.

SOLUTION: Pressure receptors are found mainly in the body's largest organ.

PROBLEM: Fact 1: Evolution occurs in response to a change in the environment. 
Fact 2: Environments reflect native habitats.

SOLUTION:
evolution occurs in response to a change in native habitats.