The increasing order of electronegativity among the following elements is:

The correct option is C boron < carbon < nitogen < oxygen < fluorine
Electronegativity is defined as the tendency of the atom of an element to gain or attract electron(s) in order to attain noble gas configuration. Boron, carbon, nitrogen, oxygen and fluorine belong to the same period (2nd period) of the modern periodic table. As we go from left to right within a period, the electronegativity increases with increase in effective nuclear charge.
Therefore, the correct order is:
boron < carbon < nitogen < oxygen < fluorine