Sentence Correction (SC) | Re: Be sure the one which you select is the one which you really know to b

If you split C into its clauses, you get
Clause 1- Be sure the one
Clause 2- that you select is the one
Clause 3- that you really know to be correct

Whereas if you split D into its clauses, you get

Clause 1- Be sure
Clause 2- that the one you select is the one you really know to be correct

The 'that' in clause 2 of option D is modifying sure, whereas the 'that' in clause 2 of option C is modifying 'one'. This is changing the intended meaning
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