In the series carbon, nitrogen, oxygen and fluorine, electronegativity:
A
decreases from carbon to fluorine
C
decreases from carbon to oxygen and then increases
D
increases from carbon to fluorine
Correct option is D. increases from carbon to fluorine
Generally, electronegativity increases as we go right and up in the periodic table so since the order is C, N, O, F in the periodic table electronegativity increases from carbon to fluorine.
Option D is correct.