Which of the following is arranged in the order of increasing connotation (intension)?

In increasing connotation the order is Vertebrates, Mammals, Canine, Labradors.

Vertebrate is the widest term with the fewest defining attributes.

Mammal adds further attributes and falls within vertebrates.

Canine narrows further, adding the marks of the dog family.

Labrador is the most specific, richest in connoted attributes.

Rising from the least connotation to the most gives vertebrates up to labradors.