Hi Chung (u post good ones aye)
Here is my explaination why A is wrong and C is correct.
The department defines a private passenger vehicle as one registered to an individual with a gross weight of less than 8000 pounds.
A - The reason A is wrong is that, this sentence makes it sound that the vehical is registered to an individual whose weight is less that 8000 pounds. Hence this is wrong
C as one that
is registered to an individual and that
has a gross weight of less than 8000 pounds - Correct one
. The inclusion of THAT in both the REGISTERED and for the WEIGHT, clearly explains it.
I hope this helps. This is to clear the difference between A and C, as for your question. The rest is already understood.
It is true that ONE+THAT is redundant.
But choice E does not flow, it is not correct...Let me put the choice E along with the orginal one. Now read it... do u see anything wrong?
The department defines a private passenger vehicle as having
a gross weight of less than 8000 pounds and registered to an individual.
Hmmm, how we explain better than this ... alright, let us look at these sentences....
a) Newtons third law defines THAT....
b) The jury defines THAT,
An example for DEFINED AS ( you would have already seen DEFINED AS, tense usage).
It cannot be, Newtons 3rd law defines as
Defines THAT and Defined AS. Sentence E does not satisfy this, hence it is OUT.
I hope you got my point
Again, GMAT tests on picking the best of the choices, even though it is redundant. C is the best choice. I hope this helps.
Giving another SHOT