A study has recently shown that happier employees are more productive. Employees at Davis Industries are more productive over the course of the business day than those at Saturnine Corporation. Therefore, we can conclude that Davis Industries' employees must be happier than those at Saturnine Corp.

The argument is most vulnerable to which of the following criticisms?

A:The evidence it uses is simply a paraphrase of its main conclusion.

B:It posits that an economic phenomenon is the effect of a psychological phenomenon.

C:It concludes that the consequence of one set of circumstances would not be produced by another.

D:It assumes that a phenomenon is the effect of an unrelated yet correlated phenomenon.

E:It claims that a conclusion is true without distinguishing this conclusion from the conditions that gave rise to it.