A. Chlorine is the most electronegative element out of the possible choices. Generally (though not 100% of the time) electronegativity increases as you go further left and up the periodic table.
Hope this helps :) remember your conversions and just practice it's fairly easy:)
I THINK it's <span>1,1-Difluorononane, or </span>

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Answer:
my probably best answer is B