The correct order of electronegativity is

The correct option is F > O > Cl > Br.

Electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself in a covalent bond. According to the Pauling scale, electronegativity values exhibit periodic trends across the periodic table:

1. Across a period (left to right): Electronegativity increases because the effective nuclear charge increases, drawing the bonding electrons closer to the nucleus.
2. Down a group (top to bottom): Electronegativity decreases because the atomic radius increases and the distance between the nucleus and the valence shell increases, leading to weaker attraction for shared electrons.

Let us look at the positions of the given elements in the periodic table:
- Fluorine (F) and Oxygen (O) belong to Period 2, in Groups 17 and 16, respectively.
- Chlorine (Cl) and Bromine (Br) belong to Group 17 (Halogens), in Periods 3 and 4, respectively.

Comparing these elements:
- Fluorine (F) is at the top-right of the periodic table (excluding noble gases), making it the most electronegative element with a Pauling value of approximately 4.0.
- Oxygen (O) is adjacent to Fluorine in Period 2 (Group 16) and has the second-highest electronegativity value of approximately 3.44.
- Chlorine (Cl) is below Fluorine in Group 17. Its electronegativity decreases down the group to approximately 3.16, which is lower than that of Oxygen.
- Bromine (Br) is below Chlorine in Group 17, so its electronegativity decreases further to approximately 2.96.

Combining these trends, we get the decreasing order of electronegativity as:
F (4.0) > O (3.44) > Cl (3.16) > Br (2.96)

Therefore, the correct order is F > O > Cl > Br.