Context: The coats of domestic dogs are of two varieties: "double" being common with dogs (as well as wolves) originating from colder climates, made up of a coarse guard hair and a soft down hair, or "single", with the topcoat only.

Question: Which coat is more common with dogs living in colder climates?
Answer: double

Question: Along with a gruff guard hair, what else makes up the double coat?
Answer: soft down hair

Question: What is the more common coat for dogs from colder climates?
Answer: double

Question: What is a single coat?
Answer: topcoat only