Answer:
A. Fluorine
"Why?"
Fluorine is the most electronegative element considering it contains 5 electrons in it's 2P shell. The optimal electron configuration of the 2P orbital contains 6 electrons. This being said, Fluorine is very close to ideal electron configuration, meaning the electrons are held very tightly to the nucleus. Hence, in summary the element Fluorine has the greatest electronegativity.
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