Juanita is a bit surprised when her professor tells the class that human genes are quite similar to the genes of dogs or cats, and that is why researchers use nonhuman animals to study human development. Juanita's professor is lecturing on the principle of phylogenetic .

CONTINUITY

Explanation:

Juanita is a bit surprised when her professor tells the class that human genes are quite similar to the genes of dogs or cats, and that is why researchers use nonhuman animals to study human development. Juanita's professor is lecturing on the principle of phylogenetic CONTINUITY.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.

answer; /// charles darwin;