I have a specific query in relation to this thread:
sc-although-no-proof-yet-exists-of-t4590.html?hilit=although%20no%20proof%20yet%20exists

Although no proof yet exists of electromagnetic fields generated by household appliances posing any health threat, mounting scientific evidence has convinced many experts that there is cause for concern.
(B) of electromagnetic fields generated by household appliances that pose any threat to health

In this thread, Ron mentions B is incorrect. Reason -> "...that pose any threat to..." is a modifier, so this sentence is actually saying that there's no proof of the existence of the electromagnetic fields themselves. that's not what it's supposed to say.

But isnt "THAT" providing an essential modifier while referring to "Proof of Electromagnetic fields".
A specific kind of proof "posing health hazard" related to the electromagnetic fields. (Also the context in this question is the same. Proof of fields posing health hazard)

I am quite sure, there is something messing up my head here and i am unable to understand the basic stuff. Can someone please help.

Let's look at B very simply:
It says:
Although no proof exists of electromagnetic fields (generated by household appliances-modifier describing fields)(that pose any threat to health-modifier describing fields)

B is saying that no proof exists of the electromagnetic fields. To repost what Ron says about this:

"if you think about the context, this should become clear. the sentence starts out with "no evidence yet exists of..."
... so, ask yourself: WHAT don't we have evidence of yet?
* we don't yet have evidence of the electromagnetic fields themselves? --> nope, that doesn't make any sense
* we don't yet have evidence of their posing a threat? --> yes, this makes more sense

_________________
Jamie Nelson
ManhattanGMAT Instructor