Contrast the case made for the savannah theory of bipedalism (also known as the "radiator theory") with the case Elaine Morgan makes for an aquatic role in human evolution. Which do you think is most plausible, and why?

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; vygtosky's theory;