Condensation is a chemical reaction in which two molecules are combined together and as a product formed a large molecule. There is also loss of small molecules in the condensation reaction. And mostly the functional groups combined in the reaction.
The other name for a condensation reaction is dehydration. As there is loss of molecule in condensation reaction, when that molecule is water it is said to be dehydration.
The wording of your question doesn't quite make sense, but a mole of an element has the same mass in grams as a single atom of that element has in amu. The mole is defined as 6.02 x10^22 things, whether they be atoms or molecules or even moles! 6.02x10^22 atoms of carbon has a mass of 12.01 g, and a single atom of carbon has a mass of 12.01 amu. Hope this helps!
Here is your answer
B. NaCl
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In option A. Na isn't present.
In option C. there are two atoms of Na
So, option B is correct
HOPE IT IS USEFUL