Reported speech thus use of "that" is required, which is in Choice C only
@sdas: you're totally wright.
Because I see may people fall in a trap in (B). So, I just want to add one more thing.
Both B & C have "that".
But B is incorrect because it changes the meaning
. "that" modifies "hypothesis", not functions
It's like: Gall's hypothesis that are localized in different part........
B doesn't make any sense because of wrong modifier
(B) Gall’s hypothesis
of different mental functions that
are localized in different parts of the brain is widely accepted today
Please +1 KUDO if my post helps. Thank you.
"Designing cars consumes you; it has a hold on your spirit which is incredibly powerful. It's not something you can do part time, you have do it with all your heart and soul or you're going to get it wrong."
Chris Bangle - Former BMW Chief of Design.