GMAT Critical Reasoning (CR) | Re: OG 2016: Intellectual Activities

I understand why B is right..
But I dont get why E is wrong.

E says that the tasks in the study were more akin to maths than to conversation.
So, the assumption behind evidence itself is wrong. It is indirectly saying evidence is not valid.
So, it is weakener..

Whats wrong in my thinking? Can anyone elaborate more on option E?

Thanks...

---